K, M = map(int, input().split())
POSSIBLE = {0}
for i in range(K):
    count, *num = list(map(int, input().split())) #1st number in count, and rest in num denoted by *
    vals = {pow(x, 2, M) for x in num} #num will be squared and its MOD M result will be stored in vals
    POSSIBLE = {(a+v)%M for a in POSSIBLE for v in vals} #Every value in vals is added with every value in POSSIBLE and then MOD M on each, finally stored in POSSIBLE
print(max(POSSIBLE))