//Let's join Kaede Takagaki Fan Club !!
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
typedef pair<int,P> P1;
typedef pair<P,P> P2;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-7
#define INF 1000000000
#define fi first
#define sc second
#define rep(i,x) for(int i=0;i<x;i++)
#define repn(i,x) for(int i=1;i<=x;i++)
#define SORT(x) sort(x.begin(),x.end())
#define ERASE(x) x.erase(unique(x.begin(),x.end()),x.end())
#define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin())
#define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin())
#define all(x) x.begin(),x.end()
template<class T>
void dmp(T a){
	rep(i,a.size()) cout << a[i] << " ";
	cout << endl;
}
template<class T>
bool chmax(T&a, T b){
	if(a < b){
		a = b;
		return 1;
	}
	return 0;
}
template<class T>
bool chmin(T&a, T b){
	if(a > b){
		a = b;
		return 1;
	}
	return 0;
}
template<class T>
void g(T &a){
	cin >> a;
}
template<class T>
void o(const T &a,bool space=false){
	cout << a << (space?' ':'\n');
}
//ios::sync_with_stdio(false);
const ll mod = 1000000007;//998244353
template<class T>
void add(T&a,T b){
	a+=b;
	if(a >= mod) a-=mod;
}
int t;
void solve(){
	int n; string s; g(n); g(s);
	
	bool ok = 0;
	rep(i,n-2){
		if(s[i] == s[i+1] && s[i] == s[i+2] && s[i] == 'o') ok = 1;
		if(s[i] == '-' && s[i+1] == 'o' && s[i+2] == 'o') ok = 1;
		if(s[i+2] == '-' && s[i+1] == 'o' && s[i] == 'o') ok = 1;
		if(s[i] == 'o' && s[i+1] == '-' && s[i+2] == 'o') ok = 1;
	}
	rep(i,n){
		if(s[i] != 'o') continue;
		int L = 0, R = 0, a;
		a = i-1;
		while(a >= 0 && s[a] == 'o'){ L++; a--; }
		a = i+1; 
		while(a < n && s[a] == 'o'){ R++; a++; }
		if(min(L,R) >= 1 && max(L,R) >= 2) ok = 1;
	}
	o(ok?"O":"X");
}
int main(){
	ios::sync_with_stdio(false);
	g(t);
	while(t--) solve();
}