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: /*
      Author : Akshat Jindal
      from NIT Jalandhar , Punjab , India
      JAI MATA DI
   */
  import java.util.*;
  
  
  import java.io.*;
  import java.math.*;
  import java.sql.Array;
  
  
  
  public class Main {
  	  static class FR{
  		  
  			BufferedReader br;
  			StringTokenizer st;
  			public FR() {
  				br = new BufferedReader(new InputStreamReader(System.in));
  			}
  			String next() 
  		    { 
  		        while (st == null || !st.hasMoreElements()) 
  		        { 
  		            try
  		            { 
  		                st = new StringTokenizer(br.readLine()); 
  		            } 
  		            catch (IOException  e) 
  		            { 
  		                e.printStackTrace(); 
  		            } 
  		        } 
  		        return st.nextToken(); 
  		    } 
  
  		    int nextInt() 
  		    { 
  		        return Integer.parseInt(next()); 
  		    } 
  
  		    long nextLong() 
  		    { 
  		        return Long.parseLong(next()); 
  		    } 
  
  		    double nextDouble() 
  		    { 
  		        return Double.parseDouble(next()); 
  		    } 
  
  		    String nextLine() 
  		    { 
  		        String str = ""; 
  		        try
  		        { 
  		            str = br.readLine(); 
  		        } 
  		        catch (IOException e) 
  		        { 
  		            e.printStackTrace(); 
  		        } 
  		        return str; 
  		    } 
  		}
  	 
  	  static long mod = (long)(1e9 + 7);
  	 
  	static void sort(long[] arr ) {
  		 ArrayList<Long> al = new ArrayList<>();
  		 for(long e:arr) al.add(e);
  		 Collections.sort(al);
  		 for(int i = 0 ; i<al.size(); i++) arr[i] = al.get(i);
  	 }
  	static void sort(int[] arr ) {
  		 ArrayList<Integer> al = new ArrayList<>();
  		 for(int e:arr) al.add(e);
  		 Collections.sort(al);
  		 for(int i = 0 ; i<al.size(); i++) arr[i] = al.get(i);
  	 }
  	static int UB(long[] arr , long find , int l , int r) {
  		while(l<=r) {
  			int m = (l+r)/2;
  			if(arr[m]<find) l = m+1;
  			else r = m-1;
  		}
  		return l;
  	}
  	static int LB(long[] arr , long find,int l ,int r ) {
  		while(l<=r) {
  			int m = (l+r)/2;
  			if(arr[m] > find) r = m-1;
  			else l = m+1;
  		}
  		return r;
  	}
  	static int UB(int[] arr , long find , int l , int r) {
  		while(l<=r) {
  			int m = (l+r)/2;
  			if(arr[m]<find) l = m+1;
  			else r = m-1;
  		}
  		return l;
  	}
  	static int LB(int[] arr , long find,int l ,int r ) {
  		while(l<=r) {
  			int m = (l+r)/2;
  			if(arr[m] > find) r = m-1;
  			else l = m+1;
  		}
  		return r;
  	}
  	 static long gcd(long a, long b)
  	  {      
  	     if (b == 0)
  	        return a;
  	     return gcd(b, a % b); 
  	  }
  	 static boolean[] prime(int num) {
  			boolean[] bool = new boolean[num];
  		     
  		      for (int i = 0; i< bool.length; i++) {
  		         bool[i] = true;
  		      }
  		      for (int i = 2; i< Math.sqrt(num); i++) {
  		         if(bool[i] == true) {
  		            for(int j = (i*i); j<num; j = j+i) {
  		               bool[j] = false;
  		            }
  		         }
  		      }
  		      if(num >= 0) {
  		    	  bool[0] = false;
  		    	  bool[1] = false;
  		      }
  		      
  		      return bool;
  		}
  	 static void sort(char[] arr) {
  		 ArrayList<Character> al = new ArrayList<Character>();
  		 for(char cc:arr) al.add(cc);
  		 Collections.sort(al);
  		 for(int i = 0 ;i<arr.length ;i++) arr[i] = al.get(i);
  		 
  	 }
  	 static long[][] ncr(int n, int k)
  	    {
  	        long C[][] = new long[n + 1][k + 1];
  	        int i, j;
  	 
  	        // Calculate  value of Binomial
  	        // Coefficient in bottom up manner
  	        for (i = 0; i <= n; i++) {
  	            for (j = 0; j <= Math.min(i, k); j++) {
  	                // Base Cases
  	                if (j == 0 || j == i)
  	                    C[i][j] = 1;
  	 
  	                // Calculate value using
  	                // previously stored values
  	                else
  	                    C[i][j] = (C[i - 1][j - 1] + C[i - 1][j])%mod;
  	            }
  	        }
  	 
  	        return C;
  	    }
  	 static long modInverse(long a, long m)
  	    {
  	        long g = gcd(a, m);
  	       
  	          return   power(a, m - 2, m);
  	        
  	    }
  	   
  	      static long power(long x, long y, long m)
  	    {
  	        if (y == 0)
  	            return 1;
  	        long p = power(x, y / 2, m) % m;
  	        p = (int)((p * (long)p) % m);
  	        if (y % 2 == 0)
  	            return p;
  	        else
  	            return (int)((x * (long)p) % m);
  	    }
  	      static class DisjointUnionSets {
  			    int[] rank, parent;
  			    int n;
  			  
  			    public DisjointUnionSets(int n)
  			    {
  			        rank = new int[n];
  			        parent = new int[n];
  			        this.n = n;
  			        makeSet();
  			    }
  			  
  			    void makeSet()
  			    {
  			        for (int i = 0; i < n; i++) {
  			          
  			            parent[i] = i;
  			        }
  			    }
  			  
  			    int find(int x)
  			    {
  			        if (parent[x] != x) {
  			        
  			            parent[x] = find(parent[x]);
  			  
  			        }
  			  
  			        return parent[x];
  			    }
  			  
  			    void union(int x, int y)
  			    {
  			        int xRoot = find(x), yRoot = find(y);
  			  
  			        if (xRoot == yRoot)
  			            return;
  			  
  			        if (rank[xRoot] < rank[yRoot])
  			  
  			            parent[xRoot] = yRoot;
  			  
  			        else if (rank[yRoot] < rank[xRoot])
  			  
  			            parent[yRoot] = xRoot;
  			  
  			        else
  			        {
  			            parent[yRoot] = xRoot;
  			  
  			            rank[xRoot] = rank[xRoot] + 1;
  			        }
  			    }
  			}
  
  /* ***************************************************************************************************************************************************/	 
  	 
  	      static FR sc = new FR();
  	 static StringBuilder sb = new StringBuilder();
  	 public static void main(String args[]) {
  		
  		 int tc = 1;
  //		  tc = sc.nextInt();
  
  		 while(tc-->0) {
  			 TEST_CASE();
  			 
  		 }
  		 
  	    System.out.println(sb);
  	 }
  	 
  	 static void TEST_CASE() {
  		
  		 Map<Character , Set<Character>> map = new HashMap<>();
  		 map.put('2', new HashSet<>());
  		 map.put('3', new HashSet<>());
  		 map.put('5', new HashSet<>());
  		 map.put('7', new HashSet<>());
  
  		boolean[] prime = prime(100);
  		 for(int i = 20 ; i<80 ; i++) {
  			 if(!prime[i]) {
  				 int a = i/10;
  				 int b = i%10;
  				 if(map.containsKey((char)('0'+a))) {
  					 map.get((char)('0'+a)).add((char)('0'+b));
  				 }
  			 }
  		 }
  		int tc = sc.nextInt();
  //		System.out.println(map);
  		while(tc-- >0) {
  			 int k = sc.nextInt();
  			 String str = sc.next();
  			 boolean ans = false;
  			 for(char cc:str.toCharArray()) {
  				 if(cc == '1' || cc == '4' || cc == '6' || cc=='8' || cc=='9') {
  					 sb.append("1\n");
  					 sb.append(cc+"\n");
  					 ans = true;
  					 break;
  				 }
  			 }
  			 if(ans) continue;
  			for(int i = 0 ; i<str.length() ; i++) {
  				char pc = str.charAt(i);
  				if(!map.containsKey(pc)) continue;
  //				System.out.println(pc);
  				for(int j = i+1 ;j<str.length() ;j++) {
  					char cc = str.charAt(j);
  					if(map.get(pc).contains(cc)) {
  						sb.append("2\n");
  						sb.append(pc+""+cc+"\n");
  						ans = true;
  						break;
  					}
  				}if(ans) break;
  			}
  			if(ans) continue;
  		
  		}
  		 
  		 
  	 }
  }
  
  
  
  
  
  