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;
  public class Solve{
  
       public static void main(String []args){
          Scanner sc = new Scanner(System.in);
          int t = sc.nextInt();
          
          while(t-- >0){
              String str = sc.next();
              String res = "NO";
              int ptr = str.length()/2;
              
              if(str.length() %2 == 0){
                       String s1 = str.substring(0, ptr);
                        String s2 = str.substring(ptr, str.length());
              
                    //  System.out.println(s1+" "+s2);
              
               if(s1.equals(s2)){
                    res = "YES";
                    }
              }
              
              System.out.println(res);
          }
       }
  }