D = int(input())
a = [int(i) for i in input().split()]
for i in range(D,3,-1):
	a[i - 2] += a[i]
	a[i] = 0
ans = 0
if len(a) >= 3 and a[2] > 0:
	ans = 2
elif len(a) >= 2 and a[1] > 0:
	ans = 1
print(ans)
print(' '.join([str(a[i]) for i in range(ans + 1)]))