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

#define int long long
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

signed main(){
	int t;
	cin >> t;

	while(t--){
		int n;
		string s;
		cin >> n;
		cin >> s;
		bool f = false;
		f |= s.find("ooo") != string::npos;
		f |= s.find("oo-") != string::npos;
		f |= s.find("-oo") != string::npos;
		f |= s.find("--o-") != string::npos;
		f |= s.find("-o--") != string::npos;
		cout << (f ? "O" : "X") << endl; 
	}

	return 0;
}