#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define all(x) x.begin(),x.end()
#define ar array
#define sz(x) ((int)x.size())
template <class T,class S> inline bool chmin(T &a,const S &b) {return (a> b? a= b, 1: 0);}
template <class T,class S> inline bool chmax(T &a,const S &b) {return (a< b? a= b, 1: 0);}
int main(){
    ios_base::sync_with_stdio(false),cin.tie(0);
    int t;
    cin >> t;
    while(t--){
        int n;
        string s;
        cin >> n >> s;
        // o-o
        // ooo
        // oo-
        // -oo
        //-o-- -oo- xoo-
        // --o-
        vector <string> arr;
        arr.push_back("o-o");
        arr.push_back("ooo");
        arr.push_back("oo-");
        arr.push_back("-oo");
        arr.push_back("-o--");
        arr.push_back("--o-");
        bool ok = false;
        for(auto ele: arr)
            if(s.find(ele) != s.npos)
                ok = true;
        cout << (ok ? "O" : "X") << "\n";
    }


    return 0;
}