import math
def isPrime(n):
  last = math.floor(n ** 0.5)
  for i in range(2, last + 1):
    if n % i == 0:
      return False
  return True


N = int(input())

if N == 0:
  print(-1)
  exit()

a = []
while N > 7:
  b = N - 1
  while not isPrime(b):
    b += 1
  a.append(b)
  N ^= (b + 1)

if N >= 4:
  a.append(3)
  N ^= 4
if N == 1:
  a.append(1)
elif N == 2:
  a.append(2)
  a.append(1)
elif N == 3:
  a.append(2)

print(len(a))
print(*a)