#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("O");}else{puts("X");}
#define MAX_N 200005

int main() {
    int T;
    cin >> T;
    rep(_,T){
        int n;
        cin >> n;
        string s;
        cin >> s;
        s = "xxx" + s + "xxx";
        n = n + 6;
        int flag = 0;
        int mode = 0;
        int cnt = 0;
        rep(i,n){
            if(s[i] == 'x'){
                mode = 0;
                cnt = 0;
            }else if(s[i] == 'o'){
                cnt++;
                if(s[i+1] != 'x' && cnt >= 3){
                    flag = 1;
                    break;
                }
                if(s[i+1] != 'x' && s[i+2] != 'x' && cnt >= 2){
                    flag = 1;
                    break;
                }
                if(mode != 0 && (cnt - mode) % 2 == 0){
                    flag = 1;
                    break;
                }
                if(mode != 0 && cnt-mode==1 && (s[i+1]!='x'||mode>=2)){
                    flag = 1;
                    break;
                }
                mode = cnt;
            }else{
                cnt++;
            }
        }

        if(flag) yn;
    }
    return 0;
}