#include <iostream>
#include <algorithm>
using namespace std;
using i64 = long long;

int n;
constexpr int inf = 987654321;
vector<int> primes;
vector<vector<int>> dp;
int m;

// i番目を見てる。今までの和は acc
int rec(int i, int acc) {
  int &res = dp[i][acc];
  if(res != -1) { return res; }
  if(i == m) {
    if(acc == n) { return res = 0; }
    return res = -inf;
  }
  res = rec(i+1, acc);
  if(acc + primes[i] <= n) {
    res = max(res, rec(i+1, acc+primes[i]) + 1);
  }
  return res;
}


int main(void) {
  scanf("%d", &n);
  vector<bool> is_prime(n+1, true);
  is_prime[0] = is_prime[1] = false;
  int sq = sqrt(n);
  for(int i=2; i<=sq; ++i) {
    if(is_prime[i]) {
      for(int j=i*i; j<=n; j+=i) {
        is_prime[j] = false;
      }
    }
  }
  for(int i=2; i<=n; ++i) {
    if(is_prime[i]) { primes.push_back(i); }
  }
  m = primes.size();
  dp.assign(m+1, vector<int>(n+1, -1));
  int res = rec(0, 0);
  if(res < 0) { res = -1; }
  printf("%d\n", res);
  return 0;
}