import itertools

inp1 = input().split()
inp2 = input().split()

seq= []
for s in inp2:
    seq.append(int(s))

allseq = list(itertools.permutations(seq))

anc = []
a = int(inp1[1])    
for s in allseq:
    a = int(inp1[1]) 
    for q in s:
        a = a % q
    anc.append(a)
print(max(anc))