k,m = map(int, input().split())
inp_list = []

for _ in range(k):
    _, *nums = map(int, input().split())
    inp_list.append([x * x % m for x in nums])

curr_results = {0}

for li in inp_list:
    new_results = set()
    for res in curr_results:
        for ele in li:
            new_results.add((res + ele) % m)
    curr_results = new_results
print(max(curr_results))