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

dig_stat = [0] * 60

for n in nums:
    ex = 59
    while ex >= 0:
        if dig_stat[ex] == True:
            ex -= 1
            continue
        modulus = 2 ** (ex + 1)
        wanted = 2 ** (ex)

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

sum = 0
for i in range(60):
    if dig_stat[i] == True or dig_stat[i] >= (2 ** (i)):
        sum |= (2 ** i)

print(sum)