import sys,random

input = lambda :sys.stdin.readline().rstrip()
mi = lambda :map(int,input().split())
li = lambda :list(mi())

N = int(input())
A = li()

g = 0
for a in A:
    g |= a

for bit in range(70):
    if g>>bit & 1==0:
        print(2**bit)
        break