N = input()
S = [list(raw_input()) for i in range(N)]


def k_rank(s):
    wins = [row.count("o") for row in S]
    wk = wins[0]
    wins = set(wins)
    rank = 0
    for w in wins:
        if w > wk:
            rank += 1
    return rank + 1


def solve(a, b):
    if a >= N:
        return k_rank(S)
    if b >= N:
        return solve(a + 1, a + 2)
    if S[a][b] != '-':
        return solve(a, b + 1)
    # Pattern A
    S[a][b] = 'o'
    S[b][a] = 'x'
    pa = solve(a, b + 1)
    S[a][b] = 'x'
    S[b][a] = 'o'
    pb = solve(a, b + 1)
    S[a][b] = '-'
    return min(pa, pb)

print(solve(0, 1))