import sys
sys.setrecursionlimit(10000000)
MOD = 10 ** 9 + 7
INF = 10 ** 15

from collections import deque,defaultdict,Counter
def main():
    N,K = map(int,input().split())
    A = list(map(int,input().split()))

    A.sort(reverse = True)
    before = defaultdict(int)
    before[K] = 1
    for a in A[:-1]:
        now = defaultdict(int)
        for k in before.keys():
            now[k] = 1
            now[k%a] = 1
        before = now
    now = defaultdict(int)
    for k in before.keys():
        now[k%A[-1]] = 1
    ans = max(now.keys())
    print(ans)
if __name__ == '__main__':
    main()