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: #include <bits/stdc++.h>
  using namespace std;
  int main() {
    int T;
    cin >> T;
    while (T--) {
      int c = 0;
      string p;
      cin >> p;
      int l = p.length();
      if (l % 2 != 0)
        cout << "NO" << endl;
      else {
        for (int i = 0; i < l / 2; i++) {
          if (p[i] == p[(l / 2) + i]) {
            c++;
          }
        }
        if (c == l / 2)
          cout << "YES" << endl;
        else
          cout << "NO" << endl;
      }
    }
    return 0;
  }
  