N = int(input())

B = [0 for i in range(70)]
A = list(map(int,input().split()))
for i in range(N):
    for j in range(70):
        if A[i] & 2**j:
            B[j] = 1

for i in range(70):
    if B[i] == 0:
        print(2**i)
        exit()