#!/usr/bin/env python3
from typing import *

def solve(n: int, s: str) -> bool:
    for t in ('ooo', 'oo-', 'o-o', '-oo', '-o--', '--o-'):
        if t in s:
            return True
    return False

# generated by online-judge-template-generator (https://github.com/kmyk/online-judge-template-generator)
def main():
    import sys
    tokens = iter(sys.stdin.read().split())
    T = int(next(tokens))
    N = [None for _ in range(T)]
    S = [None for _ in range(T)]
    for i in range(T):
        N[i] = int(next(tokens))
        S[i] = next(tokens)
    assert next(tokens, None) is None
    for i in range(T):
        ans = solve(N[i], S[i])
        print(ans and 'O' or 'X')

if __name__ == '__main__':
    main()