import sys
input = sys.stdin.readline

n=int(input())
A=list(map(int,input().split()))

X=[0]*70

for a in A:
    for i in range(70):
        if a & (1<<i) != 0:
            X[i]=1

for i in range(70):
    if X[i]==0:
        print(1<<i)
        break