D = int(input())
A = list(map(int,input().split()))
if D < 3:
    print(D)
    print(*A)
    exit()
for i in reversed(range(3,D+1)):
    A[i-2] += A[i]
    A.pop(-1)
i = 2
while i > 0:
    if A[i] == 0:
        A.pop(-1)
        i -= 1
    else:
        break
print(len(A) - 1)
print(*A)