//
// Created by yamunaku on 2020/04/03.
//

#include <bits/stdc++.h>

using namespace std;

#define rep(i, n) for(int i = 0; i < (n); i++)
#define repl(i, l, r) for(int i = (l); i < (r); i++)
#define per(i, n) for(int i = ((n)-1); i >= 0; i--)
#define perl(i, l, r) for(int i = ((r)-1); i >= (l); i--)
#define all(x) (x).begin(),(x).end()
#define MOD9 998244353
#define MOD1 1000000007
#define IINF 1000000000
#define LINF 1000000000000000000
#define SP <<" "<<
#define CYES cout<<"Yes"<<endl
#define CNO cout<<"No"<<endl
#define CFS cin.tie(0);ios::sync_with_stdio(false)
#define CST(x) cout<<fixed<<setprecision(x)

using ll = long long;
using ld = long double;
using vi = vector<int>;
using mti = vector<vector<int>>;
using vl = vector<ll>;
using mtl = vector<vector<ll>>;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
template<typename T>
using heap = priority_queue<T, vector<T>, function<bool(const T, const T)>>;

int main(){
    //CFS;
    int t;
    cin >> t;
    rep(_, t){
        int n;
        cin >> n;
        string s;
        cin >> s;
        s = "x" + s + "x";
        n += 2;
        int count = -IINF;
        rep(i, n - 2){
            string tt = s.substr(i, 3);
            if(tt == "oo-" || tt == "o-o" || tt == "-oo" || tt == "ooo"){
                cout << "O" << endl;
                goto next;
            }
        }
        rep(i, n - 3){
            string tt = s.substr(i, 4);
            if(tt == "--o-" || tt == "-o--"){
                cout << "O" << endl;
                goto next;
            }
        }
        rep(i, n){
            if(s[i] == 'x'){
                count = -IINF;
            }else if(s[i] == 'o'){
                if(count > 0 && count % 2){
                    cout << "O" << endl;
                    goto next;
                }else if(count > 0){
                    if(s[i + 1] == '-' || s[i - count - 2] == '-'){
                        cout << "O" << endl;
                        goto next;
                    }
                }
                count = 0;
            }else{
                count++;
            }
        }
        cout << "X" << endl;
        next:;
    }
    return 0;
}