#include <bits/stdc++.h>
using namespace std;

int main() {
  int n;
  string s;
  cin >> n >> s;
  
  int count = 0;
  for (int i = 0; i < n; i++) {
    if (s[i] == 'Q') count++;
    if (s[i] == 'H') {
      cout << -1 << '\n';
      return 0;
    }
  }
  
  if (sqrt(count) * sqrt(count) != count) {
    cout << -1 << '\n';
    return 0;
  }
  
  string t = "";
  for (int i = 0; i < sqrt(count); i++) t += s[i];
  string t2 = "";
  for (int i = 0; i < sqrt(count); i++) t2 += t;
  
  if (t2 != s) cout << -1 << '\n';
  else cout << t << '\n';
}