N = int(raw_input())
s = [raw_input() for _ in range(N)]

remain = []
for i in range(N):
    for j in range(i+1,N):
        if s[i][j] == "-":
            remain.append([i,j])
ans = 10
for i in range(2**len(remain)):
    win = [si.count("o") for si in s]
    for a,b in remain:
        if i & 1: win[a] += 1
        else: win[b] += 1
        i >>= 1
    ans = min(ans, sorted(k for k in set(win))[::-1].index(win[0])+1)
print ans