#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstring>
#include <deque>
#include <functional>
#include <iostream>
#include <iomanip>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include <cstdint>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pii;
#define MP make_pair
#define PB push_back
#define inf 1000000007
#define rep(i,n) for(int i = 0; i < (int)(n); ++i)
#define all(x) (x).begin(),(x).end()

template<typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val){
    std::fill( (T*)array, (T*)(array+N), val );
}
 
template<class T> inline bool chmax(T &a, T b){
    if(a<b){
        a = b;
        return true;
    }
    return false;
}

template<class T> inline bool chmin(T &a, T b){
    if(a>b){
        a = b;
        return true;
    }
    return false;
}

string a[]={"ooo","oo-","-oo","o---o","o-o","-o--","--o-"};
int main(){
    int t;
    cin >> t;
    rep(zz,t){
        int n;
        string s;
        cin >> n >> s;
        bool flag = 0;
        rep(i,7){
            int m = a[i].size();
            rep(id,n-m+1){
                bool ok = 1;
                rep(k,m){
                    if(s[id+k]!=a[i][k])ok = 0;
                }
                if(ok)flag = 1;
            }
        }
        if(flag){
            cout << "O\n";
        }else{
            cout << "X\n";
        }
    }
    return 0;
}