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.*;
  import java.io.*;
  
  public class CF762A {
      public static void main(String[] args) {
          FastReader fastReader = new FastReader();
          int t = fastReader.nextInt();//test cases count
          while(t-->0) {
              String s = fastReader.nextLine();
              process(s);
          }
      }
      static void process(String x) {
          if(x.length()%2!=0) {
              System.out.println("NO");
              return;
          }
          int mid=x.length()/2;
          for(int i=0;i<x.length()/2;i++) {
              if(x.charAt(i)!=x.charAt(mid++)) {
                  System.out.println("NO");
                  return;
              }
          }
          System.out.println("YES");
      }
  
      static class FastReader {
   
          BufferedReader br;
          StringTokenizer st;
   
          public FastReader() {
              br = new BufferedReader(
                      new InputStreamReader(System.in));
          }
   
          String next() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              return st.nextToken();
          }
   
          int nextInt() {
              return Integer.parseInt(next());
          }
   
          long nextLong() {
              return Long.parseLong(next());
          }
   
          double nextDouble() {
              return Double.parseDouble(next());
          }
   
          String nextLine() {
              String str = "";
              try {
                  str = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return str;
          }
      }
  }