1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
def gcdM(a, b):
    if (a == 0):
        return b
    return gcdM(b % a, a)


def calcNum(num, g, m, beg=0):
    for i in range(beg, m):
        for v in g[i]:
            num[v] += num[i] / len(g[i])


def fix(num, g, i):
    mult = len(g[i]) / gcdM(num[i], len(g[i]))
    # print(i, mult)
    if mult == 1:
        return calcNum(num, g, i + 1, i)
    num[0] *= mult
    num[1:] = [0] * (len(num) - 1)
    calcNum(num, g, i + 1)


def solve(g):
    if (len(g[0]) == 0):
        return 1

    num = [0] * len(g)
    num[0] = len(g[0])
    calcNum(num, g, 1)
    for i in range(1, len(g)):
        if (len(g[i]) == 0 or num[i] == 0):
            continue
        fix(num, g, i)
    return num[0]


n = int(input())
g = [[] for i in range(n)]
for v in range(n):
    l = [int(x) for x in input().split()]
    l = l[1:]
    for u in l:
        u -= 1
        g[v].append(u)

print(int(solve(g)))