#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)




vector<int> P;
void make_primes(int n)
{
	vector<bool> primes;

	primes.resize(n + 1, true);
	primes[0] = primes[1] = false;
	rep(i, 2, sqrt(n)) if (primes[i]) for (int j = 0; i * (j + 2) < n; j++)
		primes[i * (j + 2)] = false;

	rep(i, 2, n + 1) if (primes[i]) P.push_back(i);
}
//-----------------------------------------------------------------
int dp[3010][40101];
int main() {
	int N; cin >> N;
	make_primes(N + 1);

	rep(i, 0, 3010) rep(j, 0, 20101) dp[i][j] = -1;
	dp[0][0] = 0;
	rep(i, 0, P.size()) rep(j, 0, N + 1) if(0 <= dp[i][j]){
		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);
	}
	cout << dp[P.size()][N] << endl;
}