#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define repr(i, n) for (int i = (n) - 1; i >= 0; i--)
#define range(a) a.begin(), a.end()

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
  int T; cin >> T;
  while (T--) {
    int N; cin >> N;
    string S; cin >> S;
    S = "xxxxx" + S + "xxxxx";
    N = S.size();
    bool ans = false;
    ans |= S.find("ooo") != string::npos;
    ans |= S.find("o-o") != string::npos;
    ans |= S.find("oo-") != string::npos;
    ans |= S.find("-oo") != string::npos;
    int i = 0;
    while (i < N) {
      if (S[i] != 'o') {
        i++;
        continue;
      }
      int cnt = 0;
      i++;
      while (S[i] == '-') {
        i++;
        cnt++;
      }
      if (S[i] == 'x') {
        continue;
      }
      if ((cnt + 1) % 2 == 0) ans = true;
      i++;
    }
    cout << (ans ? "O" : "X") << '\n';
  }
}