N, K = map(int, input().split())

dp = [0] * (N+1)
data = []
for i in range(N):
    a, m = map(int, input().split())
    data.append((a, m))
    B = list(map(lambda x:int(x)-1, input().split()))
    if i:
        dp[i] = dp[i-1]
    for b in B:
        aa, mm = data[b]
        dp[i] = max(dp[i], dp[b]+a-aa)
print(max(dp))