/* -*- coding: utf-8 -*-
 *
 * 1016.cc:  No.1016 三目並べ - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 1000;

/* typedef */

/* global variables */

char s[MAX_N + 8], cs[MAX_N];
int ls[MAX_N];

/* subroutines */

/* main */

int main() {
  int t;
  scanf("%d", &t);

  while (t--) {
    int n;
    scanf("%d%s", &n, s + 1);
    n += 2;
    s[0] = 'x', s[n - 1] = 'x';

    int m = 0;
    for (int i = 0; i < n;) {
      int j = i + 1;
      while (j < n && s[i] == s[j]) j++;
      cs[m] = s[i], ls[m] = j - i, m++;
      i = j;
    }
    //printf("m=%d\n", m);

    bool ok = false;
    for (int i = 0; ! ok && i < m; i++) {
      if (cs[i] == 'o') {
	ok =
	  (ls[i] >= 3 ||
	   (ls[i] == 2 && (cs[i - 1] == '-' || cs[i + 1] == '-')) ||
	   (ls[i] == 1 && cs[i - 1] == '-' && cs[i + 1] == '-' &&
	    ((ls[i - 1] >= 1 && ls[i + 1] >= 2) ||
	     (ls[i - 1] >= 2 && ls[i + 1] >= 1))));
      }
      else if (cs[i] == '-') {
	ok =
	  (cs[i - 1] == 'o' && cs[i + 1] == 'o' && (ls[i] & 1));
      }
    }

    if (ok) puts("O");
    else puts("X");
  }
  return 0;
}