#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template <class T, class U> using Pa = pair<T, U>;
template <class T> using vec = vector<T>;
template <class T> using vvec = vector<vec<T>>;

void solve(){
    int N;
    cin >> N;
    string S;
    cin >> S;
    if(N<=2){
        cout << "X\n";
        return ;
    }
    int l = 0;
    bool ok = false;
    while(l<N){
        int r = l;
        while(r<N && S[l]==S[r]) r++;
        if(S[l]=='o' && r-l>=3) ok = true;
        if(S[l]=='-'){
            if(l>=2 && S[l-1]=='o' && S[l-2]=='o') ok = true;
            if(r+1<N && S[r]=='o' && S[r+1]=='o') ok = true;
            if(l>=1 && r<N && S[l-1]=='o' && S[r]=='o'){
                int len = r-l;
                if(len%2) ok = true;
            }
        }
        l = r;
    }
    cout << (ok? "O\n":"X\n");
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int T;
    cin >> T;
    while(T--){
        solve();
    }
}