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.io.IOException;
  import java.util.*;
  
  public class Main {
  
      public static Scanner keyboard = new Scanner(System.in);
  
      public static void main(String[] args) throws IOException
      {
          try{
  
              int N = keyboard.nextInt();
              keyboard.nextLine();
              for (int i = 0; i <N ; i++) {
                  String test = keyboard.nextLine();
                  String first = test.substring(0,(test.length()/2));
                  String last = test.substring((test.length()/2));
              /*System.out.println(first);
              System.out.println(last);*/
                  if (first.equals(last)){
                      System.out.println("Yes");
                  }else System.out.println("No");
              }
  
          }catch(Exception e){
              return;
          }
      }
  
  }
  