import sys
input=sys.stdin.readline

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

A=[0]*(N+1); M=[0]*(N+1)
B=[[]]

DP=[0]*(N+1)
for i in range(1,N+1):
    A[i],M[i]=map(int,input().split())
    DP[i]=DP[i-1]

    for b in map(int,input().split()):
        DP[i]=max(DP[i],DP[b]+A[i]-A[b])

print(DP[N])