#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
const ll MOD = 1e9+7;
const ll INF = 1e18;
#define rep(i,m,n) for(ll i = (m); i <= (n); i++)
#define zep(i,m,n) for(ll i = (m); i < (n); i++)
#define rrep(i,m,n) for(ll i = (m); i >= (n); i--)
#define print(x) cout << (x) << endl;
#define printa(x,m,n) for(ll i = (m); i <= n; i++){cout << (x[i]) << " ";} cout<<endl;

int main(){
    cin.tie(0); ios::sync_with_stdio(false);
    
    ll T;
    cin >> T;
    zep(t, 0, T){
        ll n; string s; cin >> n >> s;

        bool ans = false;

        zep(i, 0, n){
            if(i+2 < n && s[i] == 'o' && s[i+1] == 'o' && s[i+2] == 'o'){ans = true;}
            if(i+1 < n && s[i] == 'o' && s[i+1] == 'o' && ((i-1 >= 0 && s[i-1] == '-') || (i+2 < n && s[i+2] == '-'))){ans = true;}
            if(i+2 < n && s[i] == '-' && s[i+1] == 'o' && s[i+2] == '-' && ((i-1 >= 0 && s[i-1] == '-') || (i+3 < n && s[i+3] == '-'))){ans = true;}
        }

        ll state = 0;
        ll cnt = 0;
        zep(i, 0, n){
            if(state == 0){
                if(s[i] == 'o'){
                    state = 1;
                }
            }
            else{
                if(s[i] == 'o'){
                    if(cnt%2 == 1){ans = true;}
                    cnt = 0;
                }
                if(s[i] == 'x'){
                    state = 0;
                    cnt = 0;
                }
                if(s[i] == '-'){
                    cnt++;
                }
            }
        }
        print((ans)? "O" : "X")
    }

    
    
    
    return 0;
}