N = int(raw_input())
v = [raw_input() for _ in xrange(N)]

d = [[0 for i in xrange(N)] for i in xrange(N)]
c = 0


def getWins(d):
    wins = sum(d[0])
    lst = sorted(set([sum(d[i]) for i in xrange(N)]))
    return len(lst) - lst.index(wins)


for i in xrange(N):
    for j in xrange(i + 1, N):
        if v[i][j] == "-":
            c += 1

mn = 6
for b in xrange(1 << c):
    a = 0
    for i in xrange(N):
        for j in xrange(i + 1, N):
            if v[i][j] == "o":
                isWin = True
            elif v[i][j] == "x":
                isWin = False
            else:
                isWin = ((b >> a) & 1 == 1)
                a += 1

            if isWin:
                d[i][j] = 1
                d[j][i] = 0
            else:
                d[i][j] = 0
                d[j][i] = 1

    mn = min(mn, getWins(d))

print mn