N = int(input())
sAll = [input() for i in range(N)]

search = ["ooo", "oo-", "-oo", "-o--", "--o-"]
    
for sLine in sAll:
    n, s = sLine.split()
    
    flag = False
    for win in search:
        if win in s:
            flag = True
            break
    if "o-o" in s.replace("--", ""): flag = True
    print("O" if flag else "X")