import numpy as np

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

for i in range(D, 2, -1):
    a[i - 2] += a[i]
    a[i] = 0

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

print(ans)
print(" ".join(map(str, a[0:ans + 1])))