N=int(input())
A=list(map(int, input().split()))
a=bin(10**18+1)
d=len(a)-2
D=[0]*d
for i in A:
  a=bin(i)[2:]
  for j in range(len(a)):
    if a[-1-j]=='1':
      D[j]=1
for i in range(d):
  if D[i]==0:
    print(2**i)
    exit()