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

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

A=A[::-1]


while len(A)>0 and A[-1]==0:
    A.pop()

A=A[::-1]

print(len(A)-1)
if len(A)==0:
    print(0)
else:
    print(*A)