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 int inf = 1e9;
  const double eps = 1e-9;
  const int mod = 1e9 + 7;
  const int nax = 205;
  int powr(int x, int p) {
    if (p == 0) return 1;
    int xx = powr(x, p / 2);
    xx = (1LL * xx * xx) % mod;
    if (p & 1) xx = (1LL * xx * x) % mod;
    return xx;
  }
  int n, m;
  int lim = (1 << 9);
  void solve(int tc) {
    string ss;
    cin >> ss;
    if (ss.length() % 2) {
      cout << "NO\n";
      return;
    }
    int l = ss.length() / 2;
    for (int i = 0; i < l; ++i) {
      if (ss[i] != ss[i + l]) {
        cout << "NO\n";
        return;
      }
    }
    cout << "YES\n";
  }
  int main() {
    int tt = 1;
    scanf("%d", &tt);
    for (int i = 1; i <= tt; ++i) {
      solve(i);
    }
    return 0;
  }
  