description: During the hypnosis session, Nicholas suddenly remembered a positive integer n, which doesn't contain zeros in decimal notation. 
  
  Soon, when he returned home, he got curious: what is the maximum number of digits that can be removed from the number so that the number becomes not prime, that is, either composite or equal to one?
  
  For some numbers doing so is impossible: for example, for number 53 it's impossible to delete some of its digits to obtain a not prime integer. However, for all n in the test cases of this problem, it's guaranteed that it's possible to delete some of their digits to obtain a not prime number.
  
  Note that you cannot remove all the digits from the number.
  
  A prime number is a number that has no divisors except one and itself. A composite is a number that has more than two divisors. 1 is neither a prime nor a composite number.
  
  Input
  
  Each test contains multiple test cases.
  
  The first line contains one positive integer t (1 ≤ t ≤ 10^3), denoting the number of test cases. Description of the test cases follows.
  
  The first line of each test case contains one positive integer k (1 ≤ k ≤ 50) — the number of digits in the number.
  
  The second line of each test case contains a positive integer n, which doesn't contain zeros in decimal notation (10^{k-1} ≤ n < 10^{k}). It is guaranteed that it is always possible to remove less than k digits to make the number not prime.
  
  It is guaranteed that the sum of k over all test cases does not exceed 10^4.
  
  Output
  
  For every test case, print two numbers in two lines. In the first line print the number of digits, that you have left in the number. In the second line print the digits left after all delitions. 
  
  If there are multiple solutions, print any.
  
  Example
  
  Input
  
  
  7
  3
  237
  5
  44444
  3
  221
  2
  35
  3
  773
  1
  4
  30
  626221626221626221626221626221
  
  
  Output
  
  
  2
  27
  1
  4
  1
  1
  2
  35
  2
  77
  1
  4
  1
  6
  
  Note
  
  In the first test case, you can't delete 2 digits from the number 237, as all the numbers 2, 3, and 7 are prime. However, you can delete 1 digit, obtaining a number 27 = 3^3.
  
  In the second test case, you can delete all digits except one, as 4 = 2^2 is a composite number.
solution: import java.util.*;
  import java.util.Map.Entry;
  
  
  import java.io.*;
  import static java.util.Map.Entry.*;
  
  /* Name of the class has to be "Main" only if the class is public. */
  public class Main
  {
  	static long mod=(long) (1e9+7);  
  	public static void main (String[] args) throws Exception
  	{
  		
  		final long mod1=(long) 1e9+7;
  		Reader s=new Reader();
  		  PrintWriter pt=new PrintWriter(System.out);
  		  
  		  BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
  //		  int T=s.nextInt();
  		  int T=Integer.parseInt(br.readLine());
  //		  int T=1;
  		  
  //		  long fac[]=new long[200001];
  //		  fac[0]=1;
  //		  for(int i=1;i<=200000;i++) {
  //			  fac[i]=(fac[i-1]*i)%mod;
  //		  }
  //		  long ifac[]=new long[200001];
  //		  ifac[200000]=modInverse(fac[200000], mod);
  //		  for(int i=200000-1;i>=0;i--) {
  //			  ifac[i]=((i+1)*ifac[i+1])%mod;
  //		  }
  //		  pt.println(fac[1]);
  		  o:while(T-->0) {
  			  int k=Integer.parseInt(br.readLine());
  			  String n=br.readLine();
  			  for(int i=0;i<n.length();i++) {
  				  int d=n.charAt(i)-48;
  				  if(d==1||d==4||d==6||d==8||d==9) {
  					  pt.println(1);
  					  pt.println(d);
  					  continue o;
  				  }
  			  }
  			  for(int i=0;i<k;i++) {
  				  for(int j=i+1;j<k;j++) {
  					  int d1=n.charAt(i)-48;
  					  int d2=n.charAt(j)-48;
  					  int d=d1*10+d2;
  					  if(d%2==0||d%3==0||d%5==0||d%7==0) {
  						  pt.println(2);
  						  pt.println(d);
  						  continue o;
  					  }
  				  }
  			  }
  			  for(int i=0;i<k;i++) {
  				  for(int j=i+1;j<k;j++) {
  					  for(int k1=j+1;k1<k;k++) {
  						  int d1=n.charAt(i)-48;
  						  int d2=n.charAt(j)-48;
  						  int d3=n.charAt(k1)-48;
  						  int d=d1*100+d2*10+d3;
  						  if(isPrime(d)) {
  							  pt.println(3);
  							  pt.println(d);
  							  continue o;
  						  }
  					  }
  					  
  				  }
  			  }
  			  
  		  }
  		  
  		  
  		  pt.close();
  	}
  	
  	/**
  	 * Seive
  	 *
  	 * @param n length
  	 * @param factors factors[num] is smallest prime divisor of num
  	 * @param ar list of primes
  	 */
  	static void sieveOfEratosthenes(int n, int factors[], ArrayList<Integer> ar) 
      { 
          factors[1]=1;
          int p;
          for(p = 2; p*p <=n; p++) 
          { 
              if(factors[p] == 0) 
              { 
                  ar.add(p);
                  factors[p]=p;
                  for(int i = p*p; i <= n; i += p) 
                      if(factors[i]==0)
                          factors[i] = p; 
              } 
          }
          for(;p<=n;p++){
              if(factors[p] == 0) 
              { 
                  factors[p] = p;
                  ar.add(p);
              } 
          }
      }
  	
  	
  	static int binarySearch(int arr[], int x)
      {
          int l = 0, r = arr.length - 1;
          while (l <= r) {
              int m = l + (r - l) / 2;
    
              // Check if x is present at mid
              if (arr[m] == x)
                  return m;
    
              // If x greater, ignore left half
              if (arr[m] < x)
                  l = m + 1;
    
              // If x is smaller, ignore right half
              else
                  r = m - 1;
          }
    
          // if we reach here, then element was
          // not present
          return -1;
      }
  	
  	
  	public static int getFreq(int arr[], int n) {
  		int k=0;
  		for(int i=0;i<arr.length;i++) {
  			if(arr[i]==n)
  				k++;
  		}
  		return k;
  	}
  	
  	public static void primeFactors(int n)
      {
          // Print the number of 2s that divide n
  		HashMap<Integer, Integer> hm=new HashMap<Integer, Integer>();
          while (n%2==0)
          {
              hm.put(2, hm.getOrDefault(2, 0)+1);
              n/=2;
          }
   
          // n must be odd at this point.  So we can
          // skip one element (Note i = i +2)
          for (int i = 3; i <= Math.sqrt(n); i+= 2)
          {
              // While i divides n, print i and divide n
              while (n%i == 0)
              {
                  n /= i;
                  hm.put(i, hm.getOrDefault(i, 0)+1);
              }
          }
   
          // This condition is to handle the case whien
          // n is a prime number greater than 2
          if (n > 2)
          	hm.put(n, hm.getOrDefault(n, 0)+1);
      }
  
  
  	
  	static boolean isPartition(int arr[], int n) {
  		int sum = 0;
  	    int i, j;
  	 
  	    // Calculate sum of all elements
  	    for (i = 0; i < n; i++)
  	        sum += arr[i];
  	 
  	    if (sum % 2 != 0)
  	        return false;
  	 
  	    boolean part[][]=new boolean[sum/2+1][n+1];
  	 
  	    // initialize top row as true
  	    for (i = 0; i <= n; i++)
  	        part[0][i] = true;
  	 
  	    // initialize leftmost column, except part[0][0], as false
  	    for (i = 1; i <= sum / 2; i++)
  	        part[i][0] = false;
  	 
  	    // Fill the partition table in bottom up manner
  	    for (i = 1; i <= sum / 2; i++) {
  	        for (j = 1; j <= n; j++) {
  	            part[i][j] = part[i][j - 1];
  	            if (i >= arr[j - 1])
  	                part[i][j] = part[i][j]
  	                             || part[i - arr[j - 1]][j - 1];
  	        }
  	    }
  	    return part[sum / 2][n];
  	}
  	
  	static int setBit(int S, int j) { return S | 1 << j; }
  
  	static int clearBit(int S, int j) { return S & ~(1 << j); }
  
  	static int toggleBit(int S, int j) { return S ^ 1 << j; }
  
  	static boolean isOn(int S, int j) { return (S & 1 << j) != 0; }
  
  	static int turnOnLastZero(int S) { return S | S + 1; }
  	
  	static int turnOnLastConsecutiveZeroes(int S) { return S | S - 1; }
  	
  	static int turnOffLastBit(int S) { return S & S - 1; }
  	
  	static int turnOffLastConsecutiveBits(int S) { return S & S + 1; }
  
  	static int lowBit(int S) { return S & -S; }
  
  	static int setAll(int N) { return (1 << N) - 1; }
  
  	static int modulo(int S, int N) { return (S & N - 1); }		 //S%N, N is a power of 2
  
  	static boolean isPowerOfTwo(int S) { return (S & S - 1) == 0; }
  	
  	static boolean isWithin(long x, long y, long d, long k) {
  		return x*k*x*k + y*k*y*k <= d*d;
  	}
  	
  	static long modFact(long n, 
              long p) 
  	{ 
  		if (n >= p) 
  		 return 0; 
  		
  		long result = 1; 
  		for (int i = 1; i <= n; i++) 
  		 result = (result * i) % p; 
  		
  		return result; 
  	} 
  	static int sum(int[] arr, int n)
  	{
  	    int inc[]=new int[n+1];
  	    int dec[]=new int[n+1];
  	    inc[0] = arr[0];
  	    dec[0] = arr[0];
  
  	    for (int i = 1; i < n; i++) {
  	        for (int j = 0; j < i; j++) {
  	            if (arr[j] > arr[i]) {
  	                dec[i] = max(dec[i], inc[j] + arr[i]);
  	            }
  	            else if (arr[i] > arr[j]) {
  	                inc[i] = max(inc[i], dec[j] + arr[i]);
  	            }
  	        }
  	    }
  	    return max(inc[n - 1], dec[n - 1]);
  	}
  	static long nc2(long a) {
  		return a*(a-1)/2;
  	}
  	public static int numberOfprimeFactors(int n) 
      { 
          // Print the number of 2s that divide n 
  		HashSet<Integer> hs = new HashSet<Integer>();
          while (n%2==0) 
          { 
              hs.add(2);
              n /= 2; 
          } 
    
          // n must be odd at this point.  So we can 
          // skip one element (Note i = i +2) 
          for (int i = 3; i <= Math.sqrt(n); i+= 2) 
          { 
              // While i divides n, print i and divide n 
              while (n%i == 0) 
              { 
                  hs.add(i);
                  n /= i; 
              } 
          } 
    
          // This condition is to handle the case whien 
          // n is a prime number greater than 2 
          if (n > 2) 
              hs.add(n);
          return hs.size();
      } 
  	static long gcd(long a, long b) 
      { 
        if (b == 0) 
          return a; 
        return gcd(b, a % b);  
      } 
  
  
  
  
  	
  
  	static void reverse(int arr[],int start, int end) 
  	{ 
  		int temp; 
  		   
  		while (start < end) 
  		{ 
  		    temp = arr[start];  
  		    arr[start] = arr[end]; 
  		    arr[end] = temp; 
  		    start++; 
  		    end--; 
  		}  
  	}  
  	static void reverse(long arr[],int start, int end) 
  	{ 
  		long temp; 
  		   
  		while (start < end) 
  		{ 
  		    temp = arr[start];  
  		    arr[start] = arr[end]; 
  		    arr[end] = temp; 
  		    start++; 
  		    end--; 
  		}  
  	}  
  	static boolean isPrime(int n) 
      { 
          // Corner cases 
          if (n <= 1) return false; 
          if (n <= 3) return true; 
        
          // This is checked so that we can skip  
          // middle five numbers in below loop 
          if (n % 2 == 0 || n % 3 == 0) return false; 
        
          for (int i = 5; i * i <= n; i = i + 6) 
              if (n % i == 0 || n % (i + 2) == 0) 
              return false; 
        
          return true; 
      } 
  	static int p2(int n) {
  		int k=0;
  		while(n>1) {
  			if(n%2!=0)
  				return k;
  			n/=2;
  			k++;
  		}
  		return k;
  	}
  	static boolean isp2(int n) {
  		while(n>1) {
  			if(n%2==1)
  				return false;
  			n/=2;
  		}
  		return true;
  	}
  	static int binarySearch(int arr[], int first, int last, int key){  
  		   int mid = (first + last)/2;  
  		   while( first <= last ){  
  		      if ( arr[mid] < key ){  
  		        first = mid + 1;     
  		      }else if ( arr[mid] == key ){  
  		        return mid;  
  		      }else{  
  		         last = mid - 1;  
  		      }  
  		      mid = (first + last)/2;  
  		   }  
  		   return -1;
  		 }  
  
  	static void print(int a[][]) {
  		for(int i=0;i<a.length;i++)
  		{
  			for(int j=0;j<a[0].length;j++)
  				System.out.print(a[i][j]+" ");
  			System.out.println();
  		}
  	}
  	static int max (int x, int y) {
  		return (x > y)? x : y;
  	} 
  	static int search(Pair[] p, Pair pair) {
  		int l=0, r=p.length;
  		while (l <= r) { 
  	        int m = l + (r - l) / 2;
  	        if (p[m].compareTo(pair)==0) 
  	            return m; 
  	        if (p[m].compareTo(pair)<0) 
  	            l = m + 1; 
  	        else
  	            r = m - 1;
  	    }
  	    return -1;
  	}
  	static void pa(int a[])
  	{
  		for(int i=0;i<a.length;i++)
  			System.out.print(a[i]+" ");
  		System.out.println();
  		
  	}
  	static void pa(long a[])
  	{
  		for(int i=0;i<a.length;i++)
  			System.out.print(a[i]+" ");
  		System.out.println();
  		
  	}
  	static void reverseArray(int arr[], 
              int start, int end) 
  	{ 
  		int temp; 
  		   
  		while (start < end) 
  		{ 
  		    temp = arr[start];  
  		    arr[start] = arr[end]; 
  		    arr[end] = temp; 
  		    start++; 
  		    end--; 
  		}  
  	}     
  	static boolean isPalindrome(String s) {
  		int l=s.length();
  		for(int i=0;i<l/2;i++)
  		{
  			if(s.charAt(i)!=s.charAt(l-i-1))
  				return false;
  		}
  		return true;
  	}
  	static long nc2(long n, long m) {
  		return (n*(n-1)/2)%m;
  	}
  	static long c(long a) {
  		return a*(a+1)/2;
  	}
  	static int next(int[] arr, int target)  
      {  
          int start = 0, end = arr.length - 1;  
      
          int ans = -1;  
          while (start <= end) {  
              int mid = (start + end) / 2;  
      
              // Move to right side if target is  
              // greater.  
              if (arr[mid] < target) {
                  start = mid + 1;  
              }  
      
              // Move left side.  
              else {  
                  ans = mid;  
                  end = mid - 1;  
              }  
          }  
          return ans;  
      } 
  	
  	static int prev(Pair[] arr, int target)  
      {  
          int start = 0, end = arr.length - 1;  
      
          int ans = -1;  
          while (start <= end) {  
              int mid = (start + end) / 2;  
      
              // Move to left side if target is  
              // lesser.  
              if (arr[mid].a > target) {
                  end = mid - 1;  
              }  
      
              // Move right side.  
              else {  
                  ans = mid;  
                  start = mid + 1;  
              }  
          }  
          return ans;  
      } 
  
  	static long power(long x, long y, long p) 
      { 
          long res = 1; 
          x = x % p; 
                        
          while (y > 0) 
          { 
              if (y % 2 == 1) 
                  res = (res * x) % p; 
              y = y >> 1;
              x = (x * x) % p; 
          } 
          return  res; 
      } 
      static long modInverse(long n, long p) 
      { 
          return power(n, p-2, p); 
      } 
      static long nCrModP(long n, long r, 
                                      long p) 
      { 
          if(r>n)
          	return 0;
      	if (r == 0) 
              return 1; 
          long[] fac = new long[(int) (n+1)]; 
          fac[0] = 1; 
          for (int i = 1 ;i <= n; i++) 
              fac[i] = fac[i-1] * i % p;
          return (fac[(int) n]* modInverse(fac[(int) r], p) 
                  % p * modInverse(fac[(int) (n-r)], p) 
                                      % p) % p; 
      } 
  	static String reverse(String str)
  	{
  		return new StringBuffer(str).reverse().toString();
  	}
  
  
  
  	static long fastpow(long x, long y, long m)  
      { 
          if (y == 0) 
              return 1; 
            
          long p = fastpow(x, y / 2, m) % m; 
          p = (p * p) % m; 
        
          if (y % 2 == 0) 
              return p; 
          else
              return (x * p) % m; 
      } 
  	
  	static boolean isPerfectSquare(long l)
  	{
  		return Math.pow((long)Math.sqrt(l),2)==l;
  	}
  	
  	
  	static void merge(long[] arr, int l, int m, int r) 
      { 
          // Find sizes of two subarrays to be merged 
          int n1 = m - l + 1; 
          int n2 = r - m; 
    
          /* Create temp arrays */
          long L[] = new long [n1]; 
          long R[] = new long [n2]; 
    
          /*Copy data to temp arrays*/
          for (int i=0; i<n1; ++i) 
              L[i] = arr[l + i]; 
          for (int j=0; j<n2; ++j) 
              R[j] = arr[m + 1+ j]; 
    
    
          /* Merge the temp arrays */
    
          // Initial indexes of first and second subarrays 
          int i = 0, j = 0; 
    
          // Initial index of merged subarry array 
          int k = l; 
          while (i < n1 && j < n2) 
          { 
              if (L[i] <= R[j]) 
              { 
                  arr[k] = L[i]; 
                  i++; 
              } 
              else
              { 
                  arr[k] = R[j]; 
                  j++; 
              } 
              k++; 
          } 
    
          /* Copy remaining elements of L[] if any */
          while (i < n1) 
          { 
              arr[k] = L[i]; 
              i++; 
              k++; 
          } 
    
          /* Copy remaining elements of R[] if any */
          while (j < n2) 
          { 
              arr[k] = R[j]; 
              j++; 
              k++; 
          } 
      } 
    
      // Main function that sorts arr[l..r] using 
      // merge() 
      static void sort(int arr[], int l, int r) 
      { 
          if (l < r) 
          { 
              // Find the middle point 
              int m = (l+r)/2; 
    
              // Sort first and second halves 
              sort(arr, l, m); 
              sort(arr , m+1, r); 
    
              // Merge the sorted halves 
              merge(arr, l, m, r); 
          } 
      } 
  	static void merge(int arr[], int l, int m, int r) 
      { 
          // Find sizes of two subarrays to be merged 
          int n1 = m - l + 1; 
          int n2 = r - m; 
    
          /* Create temp arrays */
          int L[] = new int [n1]; 
          int R[] = new int [n2]; 
    
          /*Copy data to temp arrays*/
          for (int i=0; i<n1; ++i) 
              L[i] = arr[l + i]; 
          for (int j=0; j<n2; ++j) 
              R[j] = arr[m + 1+ j]; 
    
    
          /* Merge the temp arrays */
    
          // Initial indexes of first and second subarrays 
          int i = 0, j = 0; 
    
          // Initial index of merged subarry array 
          int k = l; 
          while (i < n1 && j < n2) 
          { 
              if (L[i] <= R[j]) 
              { 
                  arr[k] = L[i]; 
                  i++; 
              } 
              else
              { 
                  arr[k] = R[j]; 
                  j++; 
              } 
              k++; 
          } 
    
          /* Copy remaining elements of L[] if any */
          while (i < n1) 
          { 
              arr[k] = L[i]; 
              i++; 
              k++; 
          } 
    
          /* Copy remaining elements of R[] if any */
          while (j < n2) 
          { 
              arr[k] = R[j]; 
              j++; 
              k++; 
          } 
      } 
    
      // Main function that sorts arr[l..r] using 
      // merge() 
      static void sort(long arr[], int l, int r) 
      { 
          if (l < r) 
          { 
              // Find the middle point 
              int m = (l+r)/2; 
    
              // Sort first and second halves 
              sort(arr, l, m); 
              sort(arr , m+1, r); 
    
              // Merge the sorted halves 
              merge(arr, l, m, r); 
          } 
      } 
      static class Pair implements Comparable<Pair>{
          int a;
          int b;
          Pair(int a,int b){
              this.a=a;
   
              this.b=b;
          }   
          public int compareTo(Pair p){
              if(a>p.a)
                  return 1;
              if(a==p.a)
                  return (b-p.b);
              return -1;
          }
      }
  	static class Reader 
      { 
          final private int BUFFER_SIZE = 1 << 16; 
          private DataInputStream din; 
          private byte[] buffer; 
          private int bufferPointer, bytesRead; 
    
          public Reader() 
          { 
              din = new DataInputStream(System.in); 
              buffer = new byte[BUFFER_SIZE]; 
              bufferPointer = bytesRead = 0; 
          } 
    
          public Reader(String file_name) throws IOException 
          { 
              din = new DataInputStream(new FileInputStream(file_name)); 
              buffer = new byte[BUFFER_SIZE]; 
              bufferPointer = bytesRead = 0; 
          } 
    
          public String readLine() throws IOException 
          { 
              byte[] buf = new byte[128]; // line length 
              int cnt = 0, c; 
              while ((c = read()) != -1) 
              { 
                  if (c == '\n') 
                      break; 
                  buf[cnt++] = (byte) c; 
              } 
              return new String(buf, 0, cnt); 
          } 
    
          public int nextInt() throws IOException 
          { 
              int ret = 0; 
              byte c = read(); 
              while (c <= ' ') 
                  c = read(); 
              boolean neg = (c == '-'); 
              if (neg) 
                  c = read(); 
              do
              { 
                  ret = ret * 10 + c - '0'; 
              }  while ((c = read()) >= '0' && c <= '9'); 
    
              if (neg) 
                  return -ret; 
              return ret; 
          } 
    
          public long nextLong() throws IOException 
          { 
              long ret = 0; 
              byte c = read(); 
              while (c <= ' ') 
                  c = read(); 
              boolean neg = (c == '-'); 
              if (neg) 
                  c = read(); 
              do { 
                  ret = ret * 10 + c - '0'; 
              } 
              while ((c = read()) >= '0' && c <= '9'); 
              if (neg) 
                  return -ret; 
              return ret; 
          } 
    
          public double nextDouble() throws IOException 
          { 
              double ret = 0, div = 1; 
              byte c = read(); 
              while (c <= ' ') 
                  c = read(); 
              boolean neg = (c == '-'); 
              if (neg) 
                  c = read(); 
    
              do { 
                  ret = ret * 10 + c - '0'; 
              } 
              while ((c = read()) >= '0' && c <= '9'); 
    
              if (c == '.') 
              { 
                  while ((c = read()) >= '0' && c <= '9') 
                  { 
                      ret += (c - '0') / (div *= 10); 
                  } 
              } 
    
              if (neg) 
                  return -ret; 
              return ret; 
          } 
    
          private void fillBuffer() throws IOException 
          { 
              bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE); 
              if (bytesRead == -1) 
                  buffer[0] = -1; 
          } 
    
          private byte read() throws IOException 
          { 
              if (bufferPointer == bytesRead) 
                  fillBuffer(); 
              return buffer[bufferPointer++]; 
          } 
    
          public void close() throws IOException 
          { 
              if (din == null) 
                  return; 
              din.close(); 
          } 
      } 
  }