#include <bits/stdc++.h>

using namespace std;
#define rep(i,n) for (int i = 0; i < (int)(n); ++i)
#define rrep(i,n) for (int i = (int)(n-1); i >= 0; --i)
#define Rep(i,a,b) for (int i = a; i < b; ++i)
#define rRep(i,a,b) for (int i = a; i > b; --i)
#define fore(i,a) for(auto &i:a)
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define Bit(x,i) (((x)>>(i))&1)
using ll = long long;
using vi = vector<int>;
using vll = vector<long long>;
using vvi = vector<vi>;
using vvll = vector<vll>;
using vb = vector<bool>;
using vs = vector<string>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
struct settings{settings(){ios_base::sync_with_stdio(0); cin.tie(0); cout<<fixed<<setprecision(15);};}settingss;
const double PI = acos(-1);
const int INF = 1001001001;
const ll LINF = 1001001001001001001LL;

vector<int> Eratosthenes(int N) {
  vector<bool> is_prime(N+1);
  for(int i=0; i<=N; ++i) {
    is_prime[i] = true;
  }
  vector<int> ret;
  for(int i=2; i<=N; ++i) {
    if(is_prime[i]) {
      for(int j=2*i; j<=N; j+=i) {
        is_prime[j] = false;
      }
      ret.emplace_back(i);
    }
  }
  return ret;
}

int dp[200100];

int main() {
  int N; cin >> N;
  vi P = Eratosthenes(N);
  dp[0] = 1;
  fore(p, P) {
    rRep(i, N, -1) {
      if(i + p <= N && dp[i]) chmax(dp[i+p], dp[i]+1);
    }
  }
  cout << dp[N]-1 << endl;
}