#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}


Int isprime(Int x){
  if(x<=1) return 0;
  for(Int i=2;i*i<=x;i++)
    if(x%i==0) return 0;
  return 1;
}

//INSERT ABOVE HERE
signed main(){
  const Int MAX = 3e4;
  vector<Int> v;
  for(Int i=0;i<MAX;i++)
    if(isprime(i)) v.emplace_back(i);
  vector<Int> dp(MAX,-1);
  dp[0]=0;
  for(Int x:v){
    for(Int j=MAX-x-1;j>=0;j--)
      if(~dp[j]) chmax(dp[j+x],dp[j]+1);
  }
  
  Int n;
  cin>>n;
  cout<<dp[n]<<endl;
  return 0;
}