#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <iostream>
#include <queue>
#include <list>
#include <stack>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;

#define MAX_PRIME 21000 
bool isprime[MAX_PRIME+1]; 
vector<int> primes; 
void init_prime(){
  fill(isprime, isprime+MAX_PRIME+1, true); 
  isprime[0] = isprime[1] = false; 
  for(int i = 2; i <= MAX_PRIME; i++) { 
    if (isprime[i]) { 
      primes.push_back(i); 
      for(int j = i*2; j <= MAX_PRIME; j += i) 
      isprime[j] = false; 
    } 
  } 
}

int memo[20005];


int main(){
  ios::sync_with_stdio(false);

  init_prime();
  reverse(ALLOF(primes));
  rep(i,20005) memo[i] = -1;
  memo[0] = 0;
  rep(i,primes.size()){
    for(int j=20004; j>=0; j--){
      if(memo[j]>=0 && j+primes[i]<20005){
        memo[j+primes[i]] = max(memo[j+primes[i]], memo[j]+1);
      }
    }
  }
  
  int N;
  cin >> N;
  cout << memo[N] << endl;
  
  return 0;
}