// // Created by yamunaku on 2021/04/01. // #include <bits/stdc++.h> //#include <atcoder/all> using namespace std; //using namespace atcoder; #define rep(i, n) for(ll i = 0; i < (n); i++) #define repl(i, l, r) for(int i = (l); i < (r); i++) #define per(i, n) for(int i = ((n)-1); i >= 0; i--) #define perl(i, l, r) for(int i = ((r)-1); i >= (l); i--) #define all(x) (x).begin(),(x).end() #define MOD9 998244353 #define MOD1 1000000007 #define IINF 1000000000 #define LINF 1000000000000000000 #define SP <<" "<< #define CYES cout<<"Yes"<<endl #define CNO cout<<"No"<<endl #define CFS cin.tie(0);ios::sync_with_stdio(false) #define CST(x) cout<<fixed<<setprecision(x) using ll = long long; using ld = long double; using vi = vector<int>; using mti = vector<vector<int>>; using vl = vector<ll>; using mtl = vector<vector<ll>>; using pi = pair<int, int>; using pl = pair<ll, ll>; template<typename T> using heap = priority_queue<T, vector<T>, function<bool(const T, const T)>>; int main() { //CFS; int n; cin >> n; string s; cin >> s; ll c = 0; rep(i, n) { if (s[i] == 'Q') c++; else if (s[i] == 'H') { cout << -1 << endl; return 0; } } repl(i, 1, c + 1) { if (i * i == c) { vector<string> v; rep(j, c / i) { v.push_back(s.substr(i * j, i)); } rep(j, v.size()) { rep(k, v.size()) { if (v[j] != v[k]) { cout << -1 << endl; return 0; } } } cout << v[0] << endl; return 0; } } cout << -1 << endl; return 0; }