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;
  const long long int oo = 1e18;
  const long long int mod = 1e9 + 7;
  const int base = 31;
  const int tx[4] = {-1, 0, 1, 0};
  const int ty[4] = {0, 1, 0, -1};
  const long long int maxN = 70000 + 5;
  const long long int maxM = 8 * 4e5 + 5;
  const long long int block = 700;
  bool solve() {
    string s;
    cin >> s;
    int n = s.length();
    s = " " + s;
    if (n % 2) {
      return false;
    }
    string t1 = "";
    string t2 = "";
    for (long long int i = 1; i <= (n / 2); i++) t1 += s[i];
    for (long long int i = n / 2 + 1; i <= (n); i++) t2 += s[i];
    return t1 == t2;
  }
  int main() {
    {
      ios::sync_with_stdio(false);
      cin.tie(0);
    };
    int t = 1;
    cin >> t;
    while (t--)
      if (solve())
        cout << "YES\n";
      else
        cout << "NO\n";
    return 0;
  }
  