def main():
    n = int(input())
    s = [input() for _ in range(n)]
    ans = n
    num = n * (n - 1) // 2
    for ii in range(2 ** num):
        id_ = ii
        cnt = [0] * n
        for i in range(n):
            for j in range(i + 1, n):
                result = "ox"[id_ % 2]
                id_ //= 2
                if s[i][j] != '-' and s[i][j] != result:
                    break
                cnt[i if result == 'o' else j] += 1
            else:
                continue
            break
        else:
            cnt0 = cnt[0]
            cnt.sort(reverse=True)
            rank = 1
            for i in range(n):
                if cnt[i] == cnt0:
                    ans = min(ans, rank)
                    break
                if cnt[i] != cnt[i + 1]:
                    rank += 1
    print(ans)

if __name__ == '__main__':
    main()