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

int main() {
    int T;
    cin >> T;
    while (T--) {
        int n;
        string s;
        cin >> n >> s;
        bool win = false;
        for (int i = 0; i < n; i++) {
            string t3 = s.substr(i, 3);
            string t4 = s.substr(i, 4);
            if (t3 == "ooo" || t3 == "-oo" || t3 == "oo-" || t4 == "-o--" || t4 == "--o-") {
                win = true;
                break;
            }
        } 
        if (!win) {
            int last_o = -1;
            for (int i = 0; i < n; i++) {
                if (s[i] == 'o') {
                    if (last_o != -1 && (i - last_o) % 2 == 0) {
                        win = true;
                        break;
                    }
                    last_o = i;
                } else if (s[i] == 'x') {
                    last_o = -1;
                }
            }
        }
        cout << "XO"[win] << '\n';
    }
}