D = int(input())
A = list(map(int,input().split()))
m = {}
for i in range(D+1):
  m[i] = A[i]

for i in range(D, 2, -1):
  if m[i] == 0:
    del m[i]
    continue

  k = m[i]
  del m[i]
  m[i-2] += k

maxK = max(m.keys())
ans = []
for i in range(maxK+1):
  ans.append(m[i])

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

if len(ans) == 0:
  ans.append(0)

print(len(ans)-1)
print(*ans)