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

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

if D == 0:
    print(0)
    print(a[0])

elif a[2]:
    print(2)
    print(a[0], a[1], a[2])
elif a[1]:
    print(1)
    print(a[0], a[1])
else:
    print(0)
    print(a[0])