N = int(input())
lsA = list(map(int,input().split()))
k = 0
for i in range(N):
    k |= lsA[i]
k ^= 2**90-1
bn = bin(k)
ind = 1
for i in range(1,90):
    if bn[-i] == '1':
        ind = i
        break
print(2**(ind-1))