import re
import math

t = int(input())
for _ in range(t):
    n, line = input().split()
    if line.find('ooo') != -1 \
    or line.find('-oo') != -1 \
    or line.find('oo-') != -1 \
    or line.find('--o-') != -1 \
    or line.find('-o--') != -1 \
    or re.search('o-+o_', line) \
    or re.search('-o-+o', line):
        print('O')
    else:
        limit = int(math.log2(int(n)) + 1)
        for i in range(1, limit):
            desire = 'o' + '-'*(2**i-1) + 'o'
            if line.find(desire):
                print('O')
                continue
        print('X')