#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"};
    auto o_wins=[&](lint n,std::string&s){
        for(lint i=0;i<=n-3;i++){
            if(std::find(ok.begin(),ok.end(),s.substr(i,3))!=ok.end()){
                return true;
            }
        }
        for(lint l=0,r;l<n;l++){
            if(s.at(l)!='-')continue;
            for(r=l;r<n&&s.at(r)=='-';r++);
            if((r-l)%2==0){
                l=r-1;
                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';
    }
}