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 LongestString {
      public static void main(String[] args) {
          Scanner scanner = new Scanner(System.in);
          long cases = scanner.nextLong();
          scanner.nextLine();
          while (cases-- > 0) {
              String l = scanner.nextLine();
              Boolean flaf = true;
              char[] k = l.toCharArray();
              if (k.length % 2 == 0) {
                  int halfLength = k.length / 2;
                  for (int i = 0; i < k.length / 2; i++) {
                      if (k[i] != k[halfLength + i]) {
                          flaf = false;
                          break;
                      }
                  }
              } else {
                  flaf = false;
              }
              System.out.println(flaf ? "YES" : "NO");
          }
      }
  }
  