import sys
input=lambda: sys.stdin.readline().rstrip()
n=int(input())
def primes(n):
  is_prime=[True]*(n+1)
  is_prime[0]=False
  is_prime[1]=False
  for i in range(2,int(n**0.5)+1):
    if not is_prime[i]:
      continue
    for j in range(i*2,n+1,i):
      is_prime[j]=False
  return [i for i in range(n+1) if is_prime[i]]
P=primes(n)
m=len(P)
DP=[0]*(n+1)
DP[0]=1
for p in P:
  for i in range(n+1)[::-1]:
    if i>=p and DP[i-p]>0:
      DP[i]=max(DP[i],DP[i-p]+1)
print(DP[n]-1)