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 sb {
      public static void main(String[] args) {
          Scanner sc = new Scanner(System.in);
          int n = sc.nextInt();
          for (int i = 0; i < n; i++)
          {
              String s = sc.next();
              int flg=0;
              if (s.length() % 2 != 0 || s.length() == 1)
              {
                  System.out.println("No");
              } else
              {
                  int m = s.length()/2;
                  char[] ch = new char[m*2];
                  for (int j = 0; j < s.length(); j++)
                  {
                      ch[j] = s.charAt(j);
                  }
                  for(int k=0; k<m; k++)
                  {
                      if(ch[k]!=ch[k+m])
                      {
                          System.out.println("No");
                          flg=1;
                          break;
                      }
                  }
                  if(flg==0)
                      System.out.println("Yes");
              }
          }
      }
  }