import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import numpy as np
import itertools

N = int(readline())
A = np.frombuffer(read(),'S1').reshape(N,-1)[:,:N]

base = np.zeros((N,N),np.int32)
base[A == b'#'] = 0
base[A == b'-'] = 0
base[A == b'o'] = 1
base[A == b'x'] = -1
base.flags.writeable = False

match = []
for i,j in itertools.combinations(range(N),2):
    if base[i][j] == 0:
        match.append((i,j))

n_match = len(match)

best = N
for p in itertools.product((True,False),repeat=n_match):
    A = base.copy()
    for (i,j),bl in zip(match, p):
        if not bl:
            i,j = j,i
        A[i,j] = 1
        A[j,i] = -1
    pts = A.sum(axis=1)
    me = pts[0]
    rank = len(np.unique(pts[pts > me])) + 1
    if best > rank:
        best = rank

print(best)