#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------


int T;
int N;
string S;

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>T;
	while(T--) {
		cin>>N>>S;
		int win=0;
		FOR(i,N-2) if(S.substr(i,3)=="ooo") win=1;
		FOR(i,N-2) if(S.substr(i,3)=="oo-") win=1;
		FOR(i,N-2) if(S.substr(i,3)=="-oo") win=1;
		FOR(i,N-3) if(S.substr(i,4)=="-o--") win=1;
		FOR(i,N-3) if(S.substr(i,4)=="--o-") win=1;
		int pre=-1;
		FOR(i,N) {
			if(S[i]=='x') pre=-1;
			if(S[i]=='o') {
				if(pre>=0 && (i-pre)%2==0) win=1;
				pre=i;
			}
		}
		if(win) cout<<"O"<<endl;
		else cout<<"X"<<endl;
	}
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}