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.*;
  import java.util.*;
  
  
  public class A {
  
      public static void main(String args[]) throws IOException {
  
          FastReader sc = new FastReader();
          PrintWriter out = new PrintWriter(System.out);
  
          int tc, i, j;
          String s;
          char p;
  
          tc = sc.nextInt();
          while (tc-- > 0) {
              s=sc.nextLine();
              int n=s.length();
              if (n==1)
                  out.println("NO");
              else {
                  String b = s.substring(0, n / 2);
                  String c = s.substring(n / 2);
                  if (b.equals(c))
                      out.println("YES");
                  else
                      out.println("NO");
              }
          }
          out.close();
      }
  	
  
  
  /*--------------------------------------------------------
  ----------------------------------------------------------*/
  
  
      //Pair Class
  
      public static class Pair implements Comparable<Pair> {
          int x, y;
  
          Pair(int x, int y) {
              this.x = x;
              this.y = y;
          }
  
          @Override
          public int compareTo(Pair o) {
              return this.x - o.x;
          }
      }
  
      /*
  		FASTREADER
  	*/
      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;
          }
  
          /*DEFINED BY ME*/
  
          //READING ARRAY
          int[] readArray(int n) {
              int arr[] = new int[n];
              for (int i = 0; i < n; i++)
                  arr[i] = nextInt();
              return arr;
          }
  
          //COLLECTIONS SORT
          void sort(int arr[]) {
              ArrayList<Integer> l = new ArrayList<>();
              for (int i : arr)
                  l.add(i);
              Collections.sort(l);
              for (int i = 0; i < arr.length; i++)
                  arr[i] = l.get(i);
          }
  
          //EUCLID'S GCD
          int gcd(int a, int b) {
              if (b != 0)
                  return gcd(b, a % b);
              else
                  return a;
          }
  
          void swap(int arr[], int i, int j) {
              int temp = arr[i];
              arr[i] = arr[j];
              arr[j] = temp;
          }
      }
  }