import math
n = int(input())
data = input().strip().split()

m = 0

for i in range (n):
    data[i] = int(data[i])
    m = max(m, int(math.log2(data[i])))

m+=3
ans = 0
for j in range(m):
    s = 0
    for i in range(n):
        s += data[i] & (2**(j+1)-1)

    if (s >= 2**j):
        ans += 2**j

print(ans)