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.ArrayList;
  import java.util.Arrays;
  import java.util.Scanner;
  
  public class CodeforcesProblems { 
          public static void main(String[] args) {
          Scanner scanner = new Scanner(System.in);
          String s,s1="";
          int t;
          t=scanner.nextInt();
          scanner.nextLine();
          int n=0;
          for(int i=1; i<=t; i++){
          s=scanner.nextLine();
          n=s.length();
          if(n%2==0&&s.substring(0,n/2).equals(s.substring(n/2))){
            System.out.println("Yes");}
          else{
            System.out.println("NO");
          }
                      }
          }
        }
      
          
  
         
  
  