n = int(input())
A = list(map(int, input().split()))
N = 4*10**6+50
dp = 1
limit = (1<<N)-1
for a in A:
    dp ^= dp<<a
    dp &= limit
ans = 0
for i in range(N):
    if (dp>>i)&1:
        ans ^= i
print(ans)