import math
n = int(input())
nums = [int(x) for x in input().split(" ")]

dig_stat = [0] * 62

for n in nums:
    for ex in range(61, -1, -1):
        if dig_stat[ex] == -1:
            continue
        modulus = 1 << (ex + 1)
        wanted = 1 << (ex)

#        print(n, modulus, wanted)
        nmod = n & (modulus - 1) 
        
        if nmod >= wanted:
            dig_stat[ex] = -1
        else:
            dig_stat[ex] += nmod
            if dig_stat[ex] >= wanted:
                dig_stat[ex] = -1
        n = nmod

sum = 0
for i in range(62):
    if dig_stat[i] == -1:
        sum |= 1 << i

print(sum)