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.io.*;
  import java.util.*;
  import java.math.BigInteger;
  
  /**
   __                  __
   ( _)                ( _)
   / / \\              / /\_\_
   / /   \\            / / | \ \
   / /     \\          / /  |\ \ \
   /  /   ,  \ ,       / /   /|  \ \
   /  /    |\_ /|      / /   / \   \_\
   /  /  |\/ _ '_| \   / /   /   \    \\
   |  /   |/  0 \0\    / |    |    \    \\
   |    |\|      \_\_ /  /    |     \    \\
   |  | |/    \.\ o\o)  /      \     |    \\
   \    |     /\\`v-v  /        |    |     \\
   | \/    /_| \\_|  /         |    | \    \\
   | |    /__/_ `-` /   _____  |    |  \    \\
   \|    [__]  \_/  |_________  \   |   \    ()
   /    [___] (    \         \  |\ |   |   //
   |    [___]                  |\| \|   /  |/
   /|    [____]                  \  |/\ / / ||
   (  \   [____ /     ) _\      \  \    \| | ||
   \  \  [_____|    / /     __/    \   / / //
   |   \ [_____/   / /        \    |   \/ //
   |   /  '----|   /=\____   _/    |   / //
   __ /  /        |  /   ___/  _/\    \  | ||
   (/-(/-\)       /   \  (/\/\)/  |    /  | /
   (/\/\)           /   /   //
   _________/   /    /
   \____________/    (
  
  
   @author NTUDragons-Reborn
   */
  
  public class Solution{
      public static void main(String[] args) {
          InputStream inputStream = System.in;
          OutputStream outputStream = System.out;
          InputReader in = new InputReader(inputStream);
          PrintWriter out = new PrintWriter(outputStream);
          Task solver = new Task();
          solver.solve(in, out);
          out.close();
      }
      // main solver
      static class Task{
  
          double eps= 0.00000001;
          static final int MAXN = 1010;
          static final int MOD= 1000000007;
  
          // stores smallest prime factor for every number
          static int spf[] = new int[MAXN];
  
          static boolean[] prime;
  
          Map<Integer,Set<Integer>> dp= new HashMap<>();
  
          // Calculating SPF (Smallest Prime Factor) for every
          // number till MAXN.
          // Time Complexity : O(nloglogn)
          public void sieve()
          {
              spf[1] = 1;
              for (int i=2; i<MAXN; i++)
  
                  // marking smallest prime factor for every
                  // number to be itself.
                  spf[i] = i;
  
              // separately marking spf for every even
              // number as 2
              for (int i=4; i<MAXN; i+=2)
                  spf[i] = 2;
  
              for (int i=3; i*i<MAXN; i++)
              {
                  // checking if i is prime
                  if (spf[i] == i)
                  {
                      // marking SPF for all numbers divisible by i
                      for (int j=i*i; j<MAXN; j+=i)
  
                          // marking spf[j] if it is not
                          // previously marked
                          if (spf[j]==j)
                              spf[j] = i;
                  }
              }
          }
  
          void sieveOfEratosthenes(int n)
          {
              // Create a boolean array
              // "prime[0..n]" and
              // initialize all entries
              // it as true. A value in
              // prime[i] will finally be
              // false if i is Not a
              // prime, else true.
              prime= new boolean[n + 1];
              for (int i = 0; i <= n; i++)
                  prime[i] = true;
      
              for (int p = 2; p * p <= n; p++)
              {
                  // If prime[p] is not changed, then it is a
                  // prime
                  if (prime[p] == true)
                  {
                      // Update all multiples of p
                      for (int i = p * p; i <= n; i += p)
                          prime[i] = false;
                  }
              }
          }
  
          // A O(log n) function returning primefactorization
          // by dividing by smallest prime factor at every step
          public Set<Integer> getFactorization(int x)
          {
              if(dp.containsKey(x)) return dp.get(x);
              Set<Integer> ret = new HashSet<>();
              while (x != 1)
              {
                  if(spf[x]!=2) ret.add(spf[x]);
                  x = x / spf[x];
              }
              dp.put(x,ret);
              return ret;
          }
          // function to find first index >= x
          public int lowerIndex(List<Integer> arr, int n, int x)
          {
              int l = 0, h = n - 1;
              while (l <= h)
              {
                  int mid = (l + h) / 2;
                  if (arr.get(mid) >= x)
                      h = mid - 1;
                  else
                      l = mid + 1;
              }
              return l;
          }
          public int lowerIndex(int[] arr, int n, int x)
          {
              int l = 0, h = n - 1;
              while (l <= h)
              {
                  int mid = (l + h) / 2;
                  if (arr[mid] >= x)
                      h = mid - 1;
                  else
                      l = mid + 1;
              }
              return l;
          }
  
          // function to find last index <= y
          public int upperIndex(List<Integer> arr, int n, int y)
          {
              int l = 0, h = n - 1;
              while (l <= h)
              {
                  int mid = (l + h) / 2;
                  if (arr.get(mid) <= y)
                      l = mid + 1;
                  else
                      h = mid - 1;
              }
              return h;
          }
          public int upperIndex(int[] arr, int n, int y)
          {
              int l = 0, h = n - 1;
              while (l <= h)
              {
                  int mid = (l + h) / 2;
                  if (arr[mid] <= y)
                      l = mid + 1;
                  else
                      h = mid - 1;
              }
              return h;
          }
  
          // function to count elements within given range
          public int countInRange(List<Integer> arr, int n, int x, int y)
          {
              // initialize result
              int count = 0;
              count = upperIndex(arr, n, y) -
                      lowerIndex(arr, n, x) + 1;
              return count;
          }
  
          public int add(int a, int b){
              a+=b;
              if(a>=MOD) a-=MOD;
              else if(a<0) a+=MOD;
              return a;
          }
  
          public int mul(int a, int b){
              long res= (long)a*(long)b;
              return (int)(res%MOD);
          }
  
          public int power(int a, int b) {
              int ans=1;
              while(b>0){
                  if((b&1)!=0) ans= mul(ans,a);
                  b>>=1;
                  a= mul(a,a);
              }
              return ans;
          }
  
          int[] fact= new int[MAXN];
          int[] inv= new int[MAXN];
  
          public int Ckn(int n, int k){
              if(k<0 || n<0) return 0;
              return mul(mul(fact[n],inv[k]),inv[n-k]);
          }
  
          public int inverse(int a){
              return power(a,MOD-2);
          }
  
          public void preprocess() {
              fact[0]=1;
              for(int i=1;i<MAXN;i++) fact[i]= mul(fact[i-1],i);
              inv[MAXN-1]= inverse(fact[MAXN-1]);
              for(int i=MAXN-2;i>=0;i--){
                  inv[i]= mul(inv[i+1],i+1);
              }
          }
  
          /**
           * return VALUE of lower bound for unsorted array
           */
          public int lowerBoundNormalArray(int[] arr, int x){
              TreeSet<Integer> set= new TreeSet<>();
              for(int num: arr) set.add(num);
              return set.lower(x);
          }
          /**
           * return VALUE of upper bound for unsorted array
           */
          public int upperBoundNormalArray(int[] arr, int x){
              TreeSet<Integer> set= new TreeSet<>();
              for(int num: arr) set.add(num);
              return set.higher(x);
          }
  
          public void debugArr(int[] arr){
              for(int i: arr) out.print(i+" ");
              out.println();
          }
  
          public int rand(){
              int min=0, max= MAXN;
              int random_int = (int)Math.floor(Math.random()*(max-min+1)+min);
              return random_int;
          }
          
          InputReader in; PrintWriter out;
          
          public void solve(InputReader in, PrintWriter out) {
              this.in=in; this.out=out;
              int t=in.nextInt();
              while(t-->0){
                  solveC();
              }
          }
          public void solveC(){
              Set<Integer> prime= new HashSet<>();
              prime.add(2);
              prime.add(3);
              prime.add(5);
              prime.add(7);
              int n= in.nextInt();
              char[] s= in.nextToken().toCharArray();
              int[] cnt= new int[10];
              for (int i = 0; i < s.length; i++){
                  if (!prime.contains(s[i]-'0')){
                      out.println(1);
                      out.println(s[i]);
                      return;
                  }
                  else{
                      cnt[s[i] - '0']++;
                  }
              }
              for (int it : prime){
                  if (cnt[it] > 1){
                      out.println(2);
                      out.println(it+""+it);
                      return;
                  }
              }
              if ((int)s.length == 2){
                  out.println(2); out.println(s); return;
              }
              if ((int)s.length == 3){
                  for (int i = 0; i < 3; i++){
                      for (int j = i+1; j < 3; j++){
                          int num = (s[i] - '0') * 10 + (s[j] - '0');
                          if (ok(num)){
                              out.println(2); out.println(num); return;
                          }
                      }
                  }
                  out.println();
                  out.println(s); return;
              }
              if ((int)s.length == 4){
                  for (int i = 0; i < 3; i++){
                      for (int j = i+1; j < 3; j++){
                          int num = (s[i] - '0') * 10 + (s[j] - '0');
                          if (ok(num)){
                              out.println(2);
                              out.println(num);
                              return;
                          }
                      }
                  }
                  for (int i = 0; i < 4; i++){
                      for (int j = i+1; j < 4; j++){
                          for (int k = j+1; k < 4; k++){
                              int num = (s[i] - '0') * 100 + (s[j] - '0') * 10 + (s[k] - '0');
                              if (ok(num)){
                                  out.println(3);
                                  out.println(num);
                                  return;
                              }
                          }
                      }
                  }
                  out.println(4);
                  out.println(s);
                  return;
              }
              
          }
          public boolean ok(int num) {
              for (int i = 2; i * i <= num; i++){
                  if (num%i==0) return true;
              }
              return false;
          }
          public int _gcd(int a,  int b)
          {
  
              if(b == 0) {
                  return a;
              }
              else {
                  return _gcd(b, a % b);
              }
          }
          public int _lcm(int a, int b){
              return (a*b)/_gcd(a,b);
          }
  
      }
  
  
      static class SEG {
          public long _gcd(long a,  long  b)
          {
  
              if(b == 0) {
                  return a;
              }
              else {
                  return _gcd(b, a % b);
              }
          }
          long[] segs;
          public SEG(List<Long> a) {
              int n= a.size();
              segs= new long[4*n];
              build(0,a,0,n-1);
          }
          void build(int root, List<Long> a, int l, int r){
              if (l==r){
                  segs[root] = a.get(l); return;
              }
              int m = (l+r) >> 1;
              build(root*2+1, a, l, m);
              build(root*2+2, a, m+1, r);
              segs[root] = _gcd(segs[root*2+1], segs[root*2+2]);
          }
          long query(int root, int l, int r, int lq, int rq){
              if (lq > r || rq < l) return 0l;
              if (l >= lq && rq >= r) return segs[root];
              int m = (l+r)>>1;
              return _gcd(query(root*2+1, l, m, lq, rq),
                           query(root*2+2, m+1, r, lq, rq));
          }
      }
  
      static class Venice{
          public Map<Long,Long> m= new HashMap<>();
          public long base=0;
          public long totalValue=0;
          private int M= 1000000007;
  
          private long addMod(long a, long b){
              a+=b;
              if(a>=M) a-=M;
              return a;
          }
  
          public void reset(){
              m= new HashMap<>();
              base=0;
              totalValue=0;
          }
          public void update(long add){
              base= base+ add;
          }
          public void add(long key, long val){
              long newKey= key-base;
              m.put(newKey, addMod(m.getOrDefault(newKey,(long)0),val));
          }
      }
  
  
  
      static class Tuple implements Comparable<Tuple>{
          int x, y, z;
          public Tuple(int x, int y, int z){
              this.x= x;
              this.y= y;
              this.z=z;
          }
          @Override
          public int compareTo(Tuple o){
              return this.z-o.z;
          }
      }
  
      static class Pair implements Comparable<Pair>{
          public int x;
          public int y;
          public Pair(int x, int y){
              this.x= x;
              this.y= y;
          }
  
          @Override
          public int compareTo(Pair o) {
              return this.x-o.x;
          }
      }
  
      // public static class compareL implements Comparator<Tuple>{
      //     @Override
      //     public int compare(Tuple t1, Tuple t2) {
      //         return t2.l - t1.l;
      //     }
      // }
  
      // fast input reader class;
      static class InputReader {
          BufferedReader br;
          StringTokenizer st;
  
          public InputReader(InputStream stream) {
              br = new BufferedReader(new InputStreamReader(stream));
          }
  
          public String nextToken() {
              while (st == null || !st.hasMoreTokens()) {
                  String line = null;
                  try {
                      line = br.readLine();
                  } catch (IOException e) {
                      throw new RuntimeException(e);
                  }
                  if (line == null) {
                      return null;
                  }
                  st = new StringTokenizer(line);
              }
              return st.nextToken();
          }
  
          public int nextInt() {
              return Integer.parseInt(nextToken());
          }
          public double nextDouble(){
              return Double.parseDouble(nextToken());
          }
          public long nextLong(){
              return Long.parseLong(nextToken());
          }
          public int[] nextIntArr(int n){
              int[] arr= new int[n];
              for(int i=0;i<n;i++) arr[i]= nextInt();
              return arr;
          }
          public long[] nextLongArr(int n){
              long[] arr= new long[n];
              for(int i=0;i<n;i++) arr[i]= nextLong();
              return arr;
          }
          public List<Integer> nextIntList(int n){
              List<Integer> arr= new ArrayList<>();
              for(int i=0;i<n;i++) arr.add(nextInt());
              return arr;
          }
          public int[][] nextIntMatArr(int n, int m){
              int[][] mat= new int[n][m];
              for(int i=0;i<n;i++) for(int j=0;j<m;j++) mat[i][j]= nextInt();
              return mat;
          }
          public List<List<Integer>> nextIntMatList(int n, int m){
              List<List<Integer>> mat= new ArrayList<>();
              for(int i=0;i<n;i++){
                  List<Integer> temp= new ArrayList<>();
                  for(int j=0;j<m;j++) temp.add(nextInt());
                  mat.add(temp);
              }
              return mat;
          }
          public char[] nextStringCharArr(){
              return nextToken().toCharArray();
          }
      }
  }