description: A string is called square if it is some string written twice in a row. For example, the strings "aa", "abcabc", "abab" and "baabaa" are square. But the strings "aaa", "abaaab" and "abcdabc" are not square.
  
  For a given string s determine if it is square.
  
  Input
  
  The first line of input data contains an integer t (1 ≤ t ≤ 100) —the number of test cases.
  
  This is followed by t lines, each containing a description of one test case. The given strings consist only of lowercase Latin letters and have lengths between 1 and 100 inclusive.
  
  Output
  
  For each test case, output on a separate line:
  
    * YES if the string in the corresponding test case is square, 
    * NO otherwise. 
  
  
  
  You can output YES and NO in any case (for example, strings yEs, yes, Yes and YES will be recognized as a positive response).
  
  Example
  
  Input
  
  
  10
  a
  aa
  aaa
  aaaa
  abab
  abcabc
  abacaba
  xxyy
  xyyx
  xyxy
  
  
  Output
  
  
  NO
  YES
  NO
  YES
  YES
  YES
  NO
  NO
  NO
  YES
solution: import java.util.Scanner; 
  import java.io.*;
  public class subham
   {
    public static void main(String[] args) 
    {
      Scanner sc= new Scanner(System.in);
       int n = sc.nextInt();
       for(int i = 0 ; i < n ; i++)
       {
          String str= sc.next();
          int len = str.length();
           if (len%2!=0 || len == 1)
           {
               System.out.println("NO");  
           }
          else
           {
               int half = str.length() % 2 == 0 ? str.length()/2 : str.length()/2 + 1;
               String first = str.substring(0, half);
               String second = str.substring(half);
           
           if(first.equals(second)){
             System.out.println("YES");  
           }
           else{
             System.out.println("NO"); 
           }
          }
       }     
    }
  }
  