n = int(input())
coordinate = [ int(v) for v in input().split() ][::-1]


for i in range(n-2):
    coordinate[i+2] += coordinate[i]
    coordinate[i] = 0

zero = 0
for i in range(n):
    if coordinate[i] == 0:
        zero += 1
    else:
        break
coordinate = [ str(i) for i in coordinate ]

s = " ".join(coordinate[zero:][::-1])
print(len(coordinate[zero:])-1)
print(s)