#include <iostream>
#include <vector>
#include <algorithm>
#include <climits>
#include <cstdio>
#include <string>
using namespace std;
#define loop(i,n) for(int i = 0; i < (n); i++)
#define loops(i,f,n) for(int i = (f); i < (n); i++)
#define VEC vector<int>
#define INF INT_MAX
#define debug(a) cout<<a
// vector<VEC> v (n, VEC(n))
//loop(i,n)loop(j,n)dp[i][j]=-1;

vector<int> P;
void makeprimes(int n)
{
	vector<bool> primes;
	primes.resize(n + 1, true);
	primes[0] = primes[1] = false;
	loops(i, 2, sqrt(n)) if (primes[i]) for (int j = 0; i * (j + 2) < n; j++)
		primes[i * (j + 2)] = false;
	loops(i, 2, n + 1) if (primes[i]) P.push_back(i);
}
int main()
{
	int n;
	cin >> n;
	makeprimes(n + 1);
	vector<VEC>dp(3010, VEC(40101));
	loop(i, 3010)loop(j, 20101)dp[i][j] = -1;
	dp[0][0] = 0;
	loop(i, P.size())
	{
		loop(j, n+1)
		{
			if (dp[i][j] >= 0)
			{
				dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
				dp[i + 1][j + P[i]] = max(dp[i + 1][j + P[i]], dp[i][j] + 1);
			}
		}
	}
	printf("%d\n", dp[P.size()][n]);
	return 0;
}