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.*;
  
  /**
   * @Author: Weizhi
   * @Date: create in 2021/12/20 22:35
   * @Description:
   */
  public class Main {
      static StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
      static PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
  
      static int nextInt() throws IOException {
          in.nextToken();
          return (int) in.nval;
      }
  
      static String next() throws IOException {
          in.nextToken();
          return in.sval;
      }
  
      public static void main(String[] args) throws IOException {
          int n = nextInt();
  
          for (int i = 0; i < n; i++) {
              String s = next();
              if (s.length() % 2 == 0) {
                  if (s.substring(0, s.length() / 2).equals(s.substring(s.length() / 2))) {
                      out.println("YES");
                  } else {
                      out.println("NO");
                  }
              } else {
                  out.println("NO");
              }
          }
          out.flush();
      }
  }