#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define loop(__x, __start, __end) for(int __x = __start; __x < __end; __x++)
template <class T> bool chmax(T &a, T b) { if (a < b) {a = b; return true; } return false; }
template <typename T>  ostream& operator<<(ostream& os, const vector<T>& v)  {  for (int i = 0; i < v.size(); ++i) {  os << v[i];  if (i != v.size() - 1)  os << ' ';  } return os;  }


vector<ll> prime(int n) {
  vector<bool> ok(n+1, true);
  ok[0] = ok[1] = false;
  for (int i=1; i*i<=n; i++) {
    if (!ok[i]) continue;

    for (int j=i*2; j<=n; j+=i) {
      ok[j] = false;
    }
  }

  vector<ll> ret;
  for (int i=2; i<=n; i++)
    if (ok[i]) ret.push_back(i);
  return ret;
}

ll dp[3000][20001];

int main() {
  int n; cin >> n;
  auto P = prime(n);
  int m = P.size();
  memset(dp, -1, sizeof(dp));
  dp[0][0] = 0;
  for (int i=0; i<m; i++) {
    ll w = P[i];
    ll v = 1;
    for (int cap=0; cap<n; cap++) {
      chmax(dp[i+1][cap], dp[i][cap]);
      if (dp[i][cap] == -1) continue;
      if (cap+w>n) continue;
        // cout << i << " -> " << i+p << endl;
        // cout << dp[i] << "   " << dp[i+p] << endl;
      chmax(dp[i+1][cap+w], dp[i][cap] + v);
    }
  }

  // loop(j,0,m+1) {
  //   loop(i,0,n+1) {
  //     cout << dp[j][i] << " ";
  //   }
  //   cout << endl;
  // }

  ll ans = -1;
  loop(i,0,m+1) chmax(ans, dp[i][n]);
  cout << ans << endl;
  return 0;
}