#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

void solve(){
    int N;
    string S;
    cin >> N >> S;
    for(int i = 0; i + 2 < N; ++i){
        if(S[i] == 'o' && S[i + 1] == 'o' && S[i + 2] == 'o'){
            cout << "O\n";
            return;
        }
    }
    for(int i = 0; i < N; ++i){
        if(S[i] == '-'){
            if(i - 2 >= 0 && S[i - 2] == 'o' && S[i - 1] == 'o'){
                cout << "O\n";
                return;
            }
            if(i + 2 < N && S[i + 1] == 'o' && S[i + 2] == 'o'){
                cout << "O\n";
                return;
            }
        }
    }
    for(int i = 0; i + 1 < N; ){
        if(S[i] == 'o' && S[i + 1] == '-'){
            int cnt = 1, j = i + 2;
            while(j < N && S[j] == '-'){
                ++cnt;
                ++j;
            }
            if(j < N && S[j] == 'o' && cnt % 2 == 1){
                cout << "O\n";
                return;
            }
            i = j;
        }
        else    ++i;
    }
    cout << "X\n";
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int T;
    cin >> T;
    while(T--)  solve();
    
    return 0;
}