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

string a = "-o--";
string b = "--o-";
string c = "ooo";
string d = "oo-";
string e = "-oo";

void solve() {
    int n; string s;
    cin >> n >> s;
    auto judge = [&](int i, string &t) {
        if (i + t.size() >= n) return false;
        for (int j = 0; j < t.size(); j++) {
            if (s[i+j] != t[j]) return false; 
        }
        return true;
    };
    bool ok = false;
    for (int i = 0; i < n; i++) {
        ok |= judge(i, a);
        ok |= judge(i, b);
        ok |= judge(i, c);
        ok |= judge(i, d);
        ok |= judge(i, e);
    }
    int c = 0;
    for (int i = 0; i < n; i++) {
        if (s[i] == '-') c++;
        else {
            if ((c & 1) && c != i) {
                if (s[i-c-1] == 'o' && s[i] == 'o') {
                    ok = true;
                }
            }
            c = 0;
        }
    }
    if (ok) cout << "O\n";
    else cout << "X\n";
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int t; cin >> t;
    while (t--) solve();
    return 0;
}