from copy import deepcopy

n = int(input())
G = [list(input()) for _ in range(n)]

for i in range(n):
    if G[0][i] == '-':
        G[0][i] = 'o'
    if G[i][0] == '-':
        G[i][0] = 'x'

W = [[0, i] for i in range(n)]
M = []
for i in range(n):
    for j in range(n):
        if G[i][j] == 'o':
            W[i][0] += 1
        if i < j and G[i][j] == '-':
            M.append((i, j))

ans = n
g = len(M)
def func(W, i):
    global ans
    if i == g:
        W.sort(key=lambda x: (-x[0], x[1]))
        r = 1
        for i in range(n):
            if W[i][1] == 0:
                ans = min(ans, r)
                return
            if W[i][0] != W[i + 1][0]:
                r += 1
    x, y = M[i]
    W[x][0] += 1
    func(deepcopy(W), i + 1)
    W[x][0] -= 1
    W[y][0] += 1
    func(deepcopy(W), i + 1)
    W[y][0] -= 1

func(W, 0)
print(ans)