import sys
readline = sys.stdin.readline

N, K = map(int, readline().split())
inf = 10 ** 18
dp = [-inf] * N
dp[0] = 0
A = [0] * N
for i in range(N):
    if i:
        dp[i] = max(dp[i], dp[i - 1])
    A[i], M = map(int, readline().split())
    B = list(map(int, readline().split()))
    for b in B:
        dp[i] = max(dp[i], dp[b - 1] + A[i] - A[b - 1])
    
print(dp[-1])