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 HelloWorld{
  
      public static void main(String[] args) {
              Scanner sc = new Scanner(System.in);
              int t = sc.nextInt();
      
              while (t != 0) {
                  String m = sc.next();
                  String ans = "NO";
                  int size = m.length();
                  if (size % 2 == 0 && m.substring(0, size/2).equals(m.substring(size/2, size))) {
                      ans = "YES";
                  }
                  System.out.println(ans);
                  t--;
              }
          }
  }