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 Square_String {
      static Scanner sc = new Scanner(System.in);
      public void squa(int n){
          for(int i = 0 ; i < n ; i++){
              String s = sc.nextLine();
              if(s.length() % 2 == 1){
                  System.out.println("NO");
              }
              else{
                  boolean check = false;
                  int k = 0;
                  for(int j = s.length() / 2 ; j <= s.length() - 1 ; j++){
                      if(s.charAt(k) != s.charAt(j)){
                          check = true;
                      }
                      k++;
                  }
                  if(check){
                      System.out.println("NO");
                  }else System.out.println("YES");
              }
          }
      }
      public static void main(String[] args) {
          Square_String squareString = new Square_String();
          int n = Integer.parseInt(sc.nextLine());
          squareString.squa(n);
      }
  }
  