from sys import exit

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

if D <= 2:
    print(D)
    print(*A)
    exit()

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

Dd = 2
while not A[Dd] and Dd > 0:
    Dd -= 1
print(Dd)
print(*A[:Dd + 1])