#include<bits/stdc++.h>
#include<unordered_set>
#include<unordered_map>
using namespace std;
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef long double ld;
const ll inf=1e9+7;
const ll mod=998244353;
int main(){
    ll t;cin>>t;
    while(t){
        t--;
        ll n;string s;cin>>n>>s;
        string a="xxxx";
        string b="";
        b+=a+s+a;
        bool f=0;
        rep(i,n){
            ll c=i+4;
            if(b[c]=='o'&&b[c+1]=='-'&&b[c+2]=='o')f=1;
            if(b[c]=='o'&&b[c+1]=='o'&&b[c+2]=='-')f=1;
            if(b[c]=='-'&&b[c+1]=='o'&&b[c+2]=='o')f=1;
            if(b[c]=='o'&&b[c+1]=='o'&&b[c+2]=='o')f=1;
            if(b[c]=='o'&&b[c+1]=='-'&&b[c+2]=='o'&&b[c+3]=='-'&&b[c+4]=='o')f=1;
            if(b[c]=='-'&&b[c+1]=='o'&&b[c+2]=='-'&&b[c+3]=='-')f=1;
            if(b[c]=='-'&&b[c+1]=='-'&&b[c+2]=='o'&&b[c+3]=='-')f=1;
            if(b[c]=='o'&&b[c+1]=='-'&&b[c+2]=='-'&&b[c+3]=='-'&&b[c+4]=='o')f=1;
        }
        if(f)cout<<'O'<<endl;
        else cout<<'X'<<endl;
    }
}