# coding: utf-8
# Your code here!
import sys
read = sys.stdin.read
readline = sys.stdin.readline

n,k,*a = map(int,read().split())
a.sort(reverse=True)

N = 1<<n
ans = 0

res = [k]
for ai in a[:-1]:
    res += [r%ai for r in res]

#print(res)
#print([r%a[-1] for r in res])

print(max(r%a[-1] for r in res))