from random import shuffle
from time import time
N, K = map(int, input().split())
A = [int(a) for a in input().split()]
sTime = time()
ma = 0
while time() - sTime < 1.8:
    shuffle(A)
    s = K
    for a in A:
        s %= a
    ma = max(ma, s)
print(ma)