description: Theofanis has a string s_1 s_2 ... s_n and a character c. He wants to make all characters of the string equal to c using the minimum number of operations.
  
  In one operation he can choose a number x (1 ≤ x ≤ n) and for every position i, where i is not divisible by x, replace s_i with c. 
  
  Find the minimum number of operations required to make all the characters equal to c and the x-s that he should use in his operations.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10^4) — the number of test cases.
  
  The first line of each test case contains the integer n (3 ≤ n ≤ 3 ⋅ 10^5) and a lowercase Latin letter c — the length of the string s and the character the resulting string should consist of.
  
  The second line of each test case contains a string s of lowercase Latin letters — the initial string.
  
  It is guaranteed that the sum of n over all test cases does not exceed 3 ⋅ 10^5.
  
  Output
  
  For each test case, firstly print one integer m — the minimum number of operations required to make all the characters equal to c.
  
  Next, print m integers x_1, x_2, ..., x_m (1 ≤ x_j ≤ n) — the x-s that should be used in the order they are given.
  
  It can be proved that under given constraints, an answer always exists. If there are multiple answers, print any.
  
  Example
  
  Input
  
  
  3
  4 a
  aaaa
  4 a
  baaa
  4 b
  bzyx
  
  
  Output
  
  
  0
  1
  2
  2 
  2 3
  
  Note
  
  Let's describe what happens in the third test case: 
  
    1. x_1 = 2: we choose all positions that are not divisible by 2 and replace them, i. e. bzyx → bzbx; 
    2. x_2 = 3: we choose all positions that are not divisible by 3 and replace them, i. e. bzbx → bbbb. 
solution: import java.io.*;
  import java.util.*;
  
  public class Codeforces
  {
      public static void main(String args[])throws Exception
      {
          BufferedReader bu=new BufferedReader(new InputStreamReader(System.in));
          StringBuilder sb=new StringBuilder();
          int t=Integer.parseInt(bu.readLine());
          while(t-->0)
          {
              String s[]=bu.readLine().split(" ");
              int n=Integer.parseInt(s[0]); char c=s[1].charAt(0);
              int i;
              char x[]=bu.readLine().toCharArray();
  
              boolean ok=true;
              for(char y:x)
              ok&=y==c;
  
              ArrayList<Integer> ans=new ArrayList<>();
              if(!ok)
              {
                  //check if we can do in 1 move
                  int u[]=new int[n+1];
                  for(i=1;i<=n;i++)
                  if(x[i-1]!=c) u[i]++;
  
                  int pos=-1;
                  for(i=2;i<=n;i++)
                  {
                      int j,cn=0;
                      for(j=i;j<=n;j+=i) cn+=u[j];
                      if(cn==0) {pos=i; break;}
                  }
                  if(pos==-1) {ans.add(n); ans.add(n-1);}
                  else ans.add(pos);
              }
              
              sb.append(ans.size()+"\n");
              if(ans.size()>0)
              {
                  for(int y:ans) sb.append(y+" ");
                  sb.append("\n");
              }
          }
          System.out.print(sb);
      }
  }