N,K = map(int,input().split())
lsA = []
lsg = [[] for i in range(N)]
for i in range(N):
    A,M = map(int,input().split())
    ls = list(map(int,input().split()))
    lsA.append(A)
    for j in range(len(ls)):
        lsg[ls[j]-1].append((i,lsA[i]-lsA[ls[j]-1]))
for i in range(N-1):
    lsg[i].append((i+1,0))

cost = [0]*(N)
for i in range(N):
    c = cost[i]
    for g,v in lsg[i]:
        cost[g] = max(cost[g],c+v)

print(max(cost))