#include<bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
using namespace std;
#define pb push_back
int dy[]={0, 0, 1, -1, 1, 1, -1, -1};
int dx[]={1, -1, 0, 0, 1, -1, -1, 1};

#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define mp make_pair
#define fi first
#define sc second
ll n;

bool h[300000];

typedef ll HURUI_TYPE;
void gethurui(bool hurui[],HURUI_TYPE n){
	hurui[0] = hurui[1] = false;
	for(HURUI_TYPE i = 2;i <= n;i++)
		hurui[i] = true;
	for(HURUI_TYPE i = 2;i <= int(sqrt(n) + 0.1);i++){
		if(!hurui[i])
			continue;
		for(HURUI_TYPE j = i * 2;j <= n;j += i)
			hurui[j] = false;
	}
}

vector <ll> p;
int dp[3000][30000];

int main(){
	cin >> n;

	gethurui(h,n);

	REP(i,n + 1) {
		if(h[i]) {
			p.pb(i);
		}
	}

	REP(i,n + 1) {
		dp[0][i] = -1;
	}
	dp[0][0] = 0;

	FOR(i,1,p.size() + 1) {
		REP(j,n + 1) {
			if(0 <= j - p[i - 1] && dp[i - 1][j - p[i - 1]] >= 0) {
				dp[i][j] = max(dp[i - 1][j - p[i - 1]] + 1,dp[i - 1][j]);
			}else{
				dp[i][j] = dp[i - 1][j];
			}
		}
	}
	cout << dp[p.size()][n] << endl;
	return 0;
}