#include <bits/stdc++.h>
using namespace std;
using Int = long long;
constexpr static int mod = 1e9 + 7;
constexpr static int inf = (1 << 30) - 1;
constexpr static Int infll = (1LL << 61) - 1;
int Competitive_Programming = (ios_base::sync_with_stdio(false), cin.tie(nullptr), cout << fixed << setprecision(15), 0);
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

int main()
{
	int N, cnt = 0;
	cin >> N;
	string s;
	cin >> s;

	for (int i = 0; i < N; i++)
	{
		if (s[i] == 'Q')
			cnt++;
		if (s[i] == 'H')
		{
			cout << -1 << "\n";
			return 0;
		}
	}

	if (cnt == 0 or N % cnt != 0)
	{
		cout << -1 << "\n";
		return 0;
	}
	else
	{
		int len = N / cnt;
		string code = s.substr(0, len), ret = "";

		for (char op : code)
		{
			if (op == 'Q')
				ret += code;
		}

		if (s == ret)
		{
			cout << code;
		}
		else
		{
			cout << -1 << "\n";
		}
	}
}