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 Scratch {
  
  
  
      public static void main(String[] args) {
          try{
              Scanner sc = new Scanner(System.in);
              int T = sc.nextInt();
              while (T-->0){
                  String st = sc.next();
                  int len = st.length();
                  if (len%2==1){
                      System.out.println("NO");
                      continue;
                  }
                  int k = len/2;
                  boolean flag=true;
                  for (int i=0;i<k;i++){
                      if (st.charAt(i)!=st.charAt(i+k)){
                          flag = false;
                          break;
                      }
                  }
                  if (flag){
                      System.out.println("YES");
                  }
                  else{
                      System.out.println("NO");
                  }
              }
  
  
  
          }
          catch(Exception e){
              return;
          }
      }
  }
  
  
  