n, x, q = map(int, input().split())
ans = 0
d = [0] * (n + 1)
for _ in range(q):
    m = int(input())
    found = False
    dup = False
    f = list(map(int, input().split()))
    for fi in f:
        if fi == x:
            found = True
            break
        d[fi] += 1
    for fi in f:
        if d[fi] >= 2:
            dup = True
        d[fi] = 0
    ans += 1.0 if found else 0.5 if dup else 0.0
print(ans)