K, M = tuple(map(int, input().strip().split()))
possible = {0}
for i in range(K):
    count, *nums = list(map(int, input().split()))
    assert count == len(nums)
    vals = {pow(x, 2, M) for x in nums}
    possible = {(a + v) % M for a in possible for v in vals}
print(max(possible))