#include <cmath>
#include <iostream>
using namespace std;
int main() {
	int N;
	string S;
	cin >> N >> S;
	int B = int(sqrt(N));
	if(S == string(B * B, 'Q')) {
		cout << string(B, 'Q') << endl;
	}
	else {
		cout << -1 << endl;
	}
	return 0;
}