import numpy as np

N, K = map(int, input().split())
A = np.array(list(map(int, input().split())))

rng = np.random.default_rng()

ans = 0

for i in range(1000000):
    rng.shuffle(A)
    tmp = K
    for a in A:
        tmp %= a
    ans = max(ans, tmp)

print(ans)