#include <bits/stdc++.h>  // clang-format off
using Int = long long;
#define REP_(i, a_, b_, a, b, ...) for (Int i = (a), lim##i = (b); i < lim##i; i++)
#define REP(i, ...) REP_(i, __VA_ARGS__, __VA_ARGS__, 0, __VA_ARGS__)
struct SetupIO { SetupIO() { std::cin.tie(nullptr), std::ios::sync_with_stdio(false), std::cout << std::fixed << std::setprecision(13); } } setup_io;
#ifndef _MY_DEBUG
#define dump(...)
#endif  // clang-format on

/**
 *    author:  knshnb
 *    created: Mon Apr  6 16:35:57 JST 2020
 **/

const Int INF = 1e9;
bool ok(const std::string& s) {
    Int n = s.size();
    REP(i, n) {
        if (i + 3 <= n && s.substr(i, 3) == "ooo") return true;
        if (i + 3 <= n && s.substr(i, 3) == "oo-") return true;
        if (i + 4 <= n && s.substr(i, 4) == "-o--") return true;
    }
    return false;
}
void solve() {
    Int n;
    std::cin >> n;
    std::string s;
    std::cin >> s;
    s = "x" + s + "x";
    Int acc = -INF;
    bool O = false;
    for (char c : s) {
        if (c == 'x') {
            acc = -INF;
        } else if (c == 'o') {
            if (acc > 0 && acc % 2) O = true;
            acc = 0;
        } else {
            acc++;
        }
    }
    O |= ok(s) || ok(std::string(s.rbegin(), s.rend()));
    std::cout << (O ? "O" : "X") << "\n";
}
signed main() {
    Int T;
    std::cin >> T;
    while (T--) solve();
}