#include <bits/stdc++.h>
using namespace std;

vector<char> ans;

signed main(){
  int t;cin>>t;
  while(t--){
    bool ok=0;
    int n;string s;cin>>n>>s;
    if(n<3){ans.push_back('X');continue;}
    int cnt=0;
    for(int i=0;i<n;i++){
      if(s[i]=='o'){
        if(++cnt>=3)ok=1;
      }
      else cnt=0;
    }
    if(ok){ans.push_back('O');continue;}
    for(int i=0;i<n-2;i++)if(s.substr(i,3)=="oo-"||s.substr(i,3)=="o-o"||s.substr(i,3)=="-oo")ok=1;
    if(ok){ans.push_back('O');continue;}
    int start=0,odd=0;
    for(int i=1;i<n;i++){
      if(s[i]=='-'&&(!start)&&s[i-1]=='o'){
        start=1;
        odd=1;
        continue;
      }
      if(s[i]=='-'&&start)odd^=1;
      if(s[i]=='o'&&start){
        if(odd)ok=1;
        start=0;
      }
      if(s[i]=='x'&&start){
        start=0;
      }
    }
    if(ok){ans.push_back('O');continue;}
    start=0;
    for(int i=0;i<n;i++){
      if(s[i]=='-'&&start==0){start=1;continue;}
      if(s[i]=='x'){start=0;continue;}
      if(s[i]=='o'&&start==1){start=2;continue;}
      if(s[i]=='o'&&start==2){ok=1;continue;}
    }
    if(ok){ans.push_back('O');continue;}
    start=0;
    for(int i=0;i<n;i++){
      if(s[i]=='o'&&start==0){start=1;continue;}
      if(s[i]=='x'){start=0;continue;}
      if(s[i]=='o'&&start==1){start=2;continue;}
      if(s[i]=='-'&&start==2){ok=1;continue;}
    }
    for(int i=0;i<n-3;i++)if(s.substr(i,4)=="-o--"||s.substr(i,4)=="--o-")ok=1;
    if(ok){ans.push_back('O');continue;}
    ans.push_back('X');
  }
  for(char p:ans)cout<<p<<endl;
}