#include <bits/stdc++.h>
using namespace std;
bool solve(string &S){
  int N = S.size();
  vector<string> P;
  for (int i = 0; i < N; i++){
    if (S[i] == 'x'){
      P.push_back("");
    } else {
      P[P.size() - 1] += S[i];
    }
  }
  int C = P.size();
  for (int i = 0; i < C; i++){
    string p = P[i];
    int L = P[i].size();
    if (L < 3) continue;
    //A: -oo-でなくooを含む
    if (p != "-oo-"){
      for (int j = 0; j < L - 1; j++){
        if (p[j] == 'o' && p[j + 1] == 'o'){
          return true;
        }
      }
    }
    //B: oで始まるか終わり-o-を含む
    if (p[0] == 'o' || p[L - 1] == 'o'){
      for (int j = 1; j < L - 1; j++){
        if (p[j - 1] == '-' && p[j] == 'o' && p[j + 1] == '-'){
          return true;
        }
      }
    }
    //C: -o-でなく-o-を含む
    if (p != "-o-"){
      for (int j = 1; j < L - 1; j++){
        if (p[j - 1] == '-' && p[j] == 'o' && p[j + 1] == '-'){
          return true;
        }
      }
    }
    //D: oで始まりoで終わり長さが奇数
    if (L % 2 == 1){
      if (p[0] == 'o' && p[L - 1] == 'o'){
        return true;
      } else {
        continue;
      }
    }
  }
  return false;
}
int main(){
  int t;
  cin >> t;
  for (int i = 0; i < t; i++){
    int N;
    cin >> N;
    string S;
    cin >> S;
    S = 'x' + S + 'x';
    if (solve(S)){
      cout << 'O' << endl;
    } else {
      cout << 'X' << endl;
    }
  }
}