N = int(input())
S = [list(input()) for _ in range(N)]
l = [i for i in range(N)]
from itertools import combinations
l = combinations(l,2)
l = list(l)

all = N*(N-1)//2
now = N
for s in range(2**all):
    d = [0 for _ in range(N)]
    pi = True
    for i in range(all):
        p,q = l[i]
        w = 0
        if S[p][q]  == "-":
            if s>>i & 1:
                w = 0
            else:
                w = 1
        elif (S[p][q] == "o" and s>>i & 1) or (S[p][q] == "x" and s>>i & 1 == 0):
            if S[p][q] == "o":
                w = 0
            else:
                w = 1
        else:
            pi = False
            break
        if w == 0:
            d[p] += 1
        else:
            d[q] += 1
    if not pi:
        continue
    ll = []
    for i in range(len(d)):
        ll.append((d[i],i))
    ll.sort(key=lambda x:(-x[0],x[1]))
    a = ll[0][0]
    b = 1
    if ll[0][1] == 0:
        now = 1
        break
    for i in range(1,N):
        if ll[i-1][0] != ll[i][0]:
            b += 1
        if ll[i][1] == 0:
            now = min(now,b)
            break

print(now)