#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;

		bool no = true;
		int l = 0;

		for(int i = 0;i < n;i++){
			if(s[i] == 'o'){
				if(no){
					no = false;
				}else{
					f |= (i-l-1) % 2 != 0;
				}
				l = i;
			}else if(s[i] == 'x'){
				no = true;
			}
		}

		cout << (f ? "O" : "X") << endl; 
	}

	return 0;
}