d=int(input())
a=list(map(int,input().split()))
if d<=2:
  print(d)
  for i in range(d+1):
    a[i]=str(a[i])
  print(' '.join(a))
  exit()
a.reverse()
b=[1,0,-1,0]
for i in range(d-2):
  x=a[i]
  for j in range(4):
    a[i+j]-=x*b[j]
a.reverse()

if a[2]==0 and a[1]==0 and a[0]==0:
  print(0)
  print(0)
elif a[2]==0 and a[1]==0:
  print(0)
  print(a[0])
elif a[2]==0:
  print(1)
  print(a[0],a[1])
else:
  print(2)
  print(a[0],a[1],a[2])