import itertools

N = int(input())
S = [list(input()) for _ in range(N)]
scores = [0] * N
remains = []

for i, j in itertools.combinations(range(N), 2):
    if S[j][i] == '-':
        remains.append((j, i))
    elif S[j][i] == 'o':
        scores[j] += 1
    elif S[j][i] == 'x':
        scores[i] += 1

ans = N
for t in itertools.product((0, 1), repeat=len(remains)):
    s_copy = scores.copy()
    for i, x in enumerate(t):
        s_copy[remains[i][x]] += 1

    d = {k: v + 1 for v, k in enumerate(sorted(list(set(s_copy)), reverse=True))}
    ans = min(ans, d[s_copy[0]])

print(ans)