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 A {
      public static void main(String[] args) {
          Scanner in = new Scanner(System.in);
          int t = in.nextInt();
          while (t-- > 0){
              String s = in.next();
              System.out.println(test(s) ? "YES" : "NO");
          }
  
          
      }
  
      static boolean test(String s){
          int n = s.length();
          if(n % 2 == 0){
              for (int i = 0, j = n / 2; i < n / 2 && j < n; i++, j++) {
                      if (s.charAt(i) != s.charAt(j))return false;
              }
          }
          else return false;
          return true;
      }
  }
  