T = int(input())
for _ in range(T):
    N, S = input().split()
    N = int(N)
    # Check if current S has 'ooo'
    has_ooo = False
    for i in range(len(S) - 2):
        if S[i] == S[i+1] == S[i+2] == 'o':
            has_ooo = True
            break
    if has_ooo:
        print('O')
        continue
    # Check if any '-' can form 'ooo' when filled by 'o'
    possible = False
    for i in range(len(S)):
        if S[i] == '-':
            # Check left two
            if i >= 2 and S[i-2] == 'o' and S[i-1] == 'o':
                possible = True
                break
            # Check middle
            if i >= 1 and i + 1 < len(S) and S[i-1] == 'o' and S[i+1] == 'o':
                possible = True
                break
            # Check right two
            if i + 2 < len(S) and S[i+1] == 'o' and S[i+2] == 'o':
                possible = True
                break
    print('O' if possible else 'X')