#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <string.h>
#include <vector>
using namespace std;

#define ll long long
#define INF (1 << 30)
#define INFLL (1LL << 60)

#define FOR(i,a,b) for(ll i = (a);i<(b);i++)
#define REP(i,a) FOR(i,0,(a))
#define MP make_pair

int memo[2500][20000] = {};
vector<int> sosu;
int n;

bool isSosu(int a){
	for(int i = 2;i * i <= a;i++){
		if(a % i == 0) return false;
	}
	return true;
}

void init(){
	bool used[20010] = {};
	for(int i = 2;i < 20010;i++){
		if(used[i]) continue;
		if(isSosu(i)){
			sosu.push_back(i);
			for(int j = i;j < 20010;j *= 2){
				used[j] = true;
			}
		}
	}
	memset(memo, -1, sizeof(memo));
}
//2500*20000
int saiki(int index, int now){
	if(now == n) return 0;
	else if(now > n || index >= sosu.size()) return -INF;

	if(memo[index][now] != -1) return memo[index][now];

	int a, b;
	a = saiki(index + 1, now + sosu[index]) + 1;
	b = saiki(index + 1, now);

	return memo[index][now] = max(a, b);
}

int main() {
	init();
	// cout << sosu.size() << endl;
	cin >> n;
	// for(int i = 0;i < 10;i++){
	// 	cout << sosu[i] << " ";
	// }
	int ans = saiki(0, 0);

	if(ans < 0) cout << -1 << endl;
	else cout << ans << endl;
	return 0;
}