#include<bits/stdc++.h>
using lint=long long;
using real=long double;
int main(){
    std::cin.tie(nullptr);std::ios_base::sync_with_stdio(false);
    std::cout.setf(std::ios_base::fixed);std::cout.precision(15);
    std::vector<std::string>ok={"ooo","oo-","-oo","-o--","--o-"};
    auto o_wins=[&](lint n,std::string&s){
        for(auto&&t:ok){
            for(lint i=0;i<=n;i++){
                if(s.substr(i,t.length())==t){
                    return true;
                }
            }
        }
        for(lint l=0,r=0;l<n;){
            for(l=r;l<n&&s.at(l)!='-';l++);
            for(r=l;r<n&&s.at(r)=='-';r++);
            if((r-l)%2==0)continue;
            if(l&&s.at(l-1)=='o'&&r<n&&s.at(r)=='o'){
                return true;
            }
        }
        return false;
    };
    lint q;std::cin>>q;
    while(q--){
        lint n;std::string s;std::cin>>n>>s;
        n+=2;
        s="x"+s+"x";
        std::cout<<(o_wins(n,s)?"O":"X")<<'\n';
    }
}