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

int main(){
    int T;
    cin >> T;
    vector<string> cases = {"-oo", "oo-", "ooo", "o---o", "o-o", "-o--o", "o--o-"};
    for (int t = 0; t < T; t++){
        int n;
        string S;
        cin >> n >> S;
        bool flag = false;
        for (const auto &c: cases){
            flag |= S.find(c) != string::npos;
        }
        puts(flag ? "O" : "X");
    }
}