import sys
input = sys.stdin.buffer.readline
sys.setrecursionlimit(10 ** 7)

N, K = map(int, input().split())
G = [[] for _ in range(N)]
A = [0] * N
for i in range(N):
    A[i], M = map(int, input().split())
    for b in map(int, input().split()):
        G[i].append(b-1)

dp = [0] * N
for i in range(1, N):
    for j in G[i]:
        dp[i] = max(dp[i], dp[j] + A[i] - A[j])
    dp[i] = max(dp[i], dp[i-1])

print(dp[N-1])