from sys import stdin
n, *a = map(int, stdin.read().split())
appearbit = [0 for i in range(63)]
for i in range(n):
    for j in range(63):
        if a[i] & 1:
            appearbit[j] = appearbit[j] | 1
        a[i] = a[i] >> 1

for i in range(63):
    if appearbit[i] == 0:
        ans = 1 << i
        print("{}".format(ans))
        exit()

ans = 1 << 63
print("{}".format(ans))