#include "bits/stdc++.h"
 
using namespace std;
typedef long long ll;
typedef vector<ll> vll;
#define int ll
#define fi first
#define se second
#define SORT(a) sort(a.begin(),a.end())
#define rep(i,n) for(int i = 0;i < (n) ; i++) 
#define REP(i,n) for(int i = 0;i < (n) ; i++) 
#define MP(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define INF LLONG_MAX/2
#define all(x) (x).begin(),(x).end()
#define debug(x) cerr<<#x<<": "<<x<<endl
#define debug_vec(v) cerr<<#v<<":";rep(i,v.size())cerr<<" "<<v[i];cerr<<endl
//----------------------------------------------------------------

// int MOD = 998244353;
int MOD = 1000000007;

ll dp[2300][20001] = {0};

//----------------------------------------------------------------
signed main(){

	ll N;
	cin >> N;
	N++;
	//arr[i] == 1  ->  i は素数
    int arr[200010];
    for(int i = 0; i < N; i++) arr[i] = 1;
    for(int i = 2; i < sqrt(N); i++){
        if(arr[i]){
            for(int j = 0; i * (j + 2) < N; j++){
                arr[i *(j + 2)] = 0;
            }
        }
    }
	vector<int> pri;
    arr[0] = 0;
    arr[1] = 0;
    for(int i = 2; i < N; i++){
        if(arr[i]){
			pri.pb(i);
        }
    }
	// for(auto x:pri)cout << x << endl;
	// cout << endl;

	N--;
	rep(i,N) dp[0][i+1] = -INF;

	for(int i = 1;i <= pri.size();i++){
		for(int j = 1;j <= N;j++){
			dp[i][j] = dp[i-1][j];
			if(j-pri[i-1] >= 0)dp[i][j] = max(dp[i-1][j],dp[i-1][j-pri[i-1]]+1);
		}
	}
	if(dp[pri.size()][N] < -30000)cout << -1 << endl;
	else cout << dp[pri.size()][N] << endl;


	// rep(i,pri.size()){
	// 	cout << pri[i] << " : ";
	// 	rep(j,N+1){
	// 		if(dp[i+1][j] == -1)cout << -1 << " ";
	// 		else cout << dp[i+1][j] << " ";
	// 	}
	// 	cout << endl;
	// }



	

	return 0;
}

//----------------------------------------------------------------

// g++ -std=c++14 code1.cpp
// rm -r -f test;oj dl https://code-festival-2018-quala.contest.atcoder.jp/tasks/code_festival_2018_quala_c
// rm -r -f test;oj dl https://dp.contest.atcoder.jp/tasks/dp_a
// rm -r -f test;oj dl http://arc092.contest.atcoder.jp/tasks/arc092_b