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.*;
  public class SquareString
  {
    public static void main(String[] args)
    {
      Scanner input = new Scanner(System.in);
      int x = input.nextInt();
      input.nextLine();
      for (int i = 0; i < x; i++)
      {
        String a = input.nextLine();
        char[] b = a.toCharArray();
        boolean c = true;
        if (b.length % 2 == 0)
        {
          for (int o = 0; o < b.length/2; o++)
          {
            if (b[o] != b[o + b.length/2])
            {
              System.out.println("NO");
              c = false;
              break;
            }
          }
          if (c == true)
          {
            System.out.println("YES");
          }
        }
        else
        {
          System.out.println("NO");
        }
      }
    }
  }