D = int(input())
a = list(map(int, input().split()))

for i in range(D, 2, -1):
    a[i - 2] += a[i]

ans = 0
if len(a) >= 3:
    if a[2]:
        ans = 2
    elif a[1]:
        ans = 1
print(ans)

for i in range(ans + 1):
    if ans == i:
        print(a[i])
    else:
        print(a[i], end=' ')