# include <iostream>
# include <algorithm>
# include <vector>
# include <string>
# include <set>
# include <map>
# include <cmath>
# include <iomanip>
# include <functional>
# include <utility>
# include <stack>
# include <queue>
# include <list>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
constexpr long long MOD = 1000000000 + 7;
constexpr long long INF = 100000000000000;
const double PI = acos(-1);

int dp[2300][20000];

std::vector<int> prime;
void MakePrime(int n) {
	prime.emplace_back(2);
	for (int i = 3; i < n; i += 2) {
		bool a = false;
		for (int j = 3; j <= std::sqrt(i); j += 2) {
			if (i%j == 0) {
				a = true;
			}
		}
		if (a == false) {
			prime.emplace_back(i);
		}
	}
}

int main() {
	MakePrime(20000);
	int n;
	cin >> n;
	for (int i = 0; i < 1500; i++) {
		for (int j = 0; j < 15000; j++) {
			dp[i][j] = -1;
		}
	}
	dp[0][0] = 0;
	for (int i = 0; i < prime.size(); i++) {
		for (int j = 0; j <= n; j++) {
			if (dp[i][j] == -1)continue;
			if (j + prime[i] <= n)dp[i + 1][j + prime[i]] = max(dp[i + 1][j + prime[i]], dp[i][j] + 1);
			dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
		}
	}
	cout << dp[prime.size()][n] << endl;
}