n = int(input())
A = list(map(int, input().split()))
N = max(A)*n+1
dp = 1
for a in A:
    dp ^= dp<<a

ans = 0
b = bin(dp)
l = len(b)
for i in range(2, l):
    if b[i] == '1':
        ans ^= i-2
print(ans)