N = int(input())

g = [list(input()) for _ in range(N)]

def dfs(g, yx):
	if yx == N * N:
		win = [0] * N
		for i in range(N):
			for j in range(N):
				if g[i][j] == 'o':
					win[i] += 1
		res = 0
		for x in set(win):
			if win[0] == x:
				return len(set(win)) - res
			res += 1

	y, x = yx // N, yx % N
	if g[y][x] != '-':
		return dfs(g, yx + 1)

	res = 100

	g[y][x], g[x][y] = 'o', 'x'
	res = min(res, dfs(g, yx + 1))

	g[y][x], g[x][y] = 'x', 'o'
	res = min(res, dfs(g, yx + 1))

	g[y][x], g[x][y] = '-', '-'

	return res

print(dfs(g, 0))