// No.458 異なる素数の和
// https://yukicoder.me/problems/no/458
//

#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <chrono>
using namespace std;


vector<bool> create_prime_list(unsigned int limit);
int solve(unsigned int n, vector<int> &primes);

vector<bool> create_prime_list(unsigned int limit) {
    // エラトステネスの篩
    vector<bool> isprime(limit+1, true);
    isprime[0] = false;
    isprime[1] = false;

    for (auto i = 2; i <= sqrt(limit); ++i) {
        if (isprime[i]) {
            int j = i + i;
            while (j <= limit) {
                isprime[j] = false;
                j += i;
            }
        }
    }
    return isprime;
}



int dp[3000][20001];

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    unsigned int n;
    cin >> n;

    // chrono::system_clock::time_point s = chrono::system_clock::now();

    // 素数リストの作成
    vector<bool> res = create_prime_list(n);
    vector<int> primes;
    for (auto i = 2; i < res.size(); ++i) {
        if (res[i])
            primes.push_back(i);
    }

    int ans = solve(n, primes);
    cout << ans << endl;

    // chrono::system_clock::time_point t = chrono::system_clock::now();
    // chrono::milliseconds mss = chrono::duration_cast<chrono::milliseconds> (s.time_since_epoch());
    // chrono::milliseconds mst = chrono::duration_cast<chrono::milliseconds> (t.time_since_epoch());
    // cout << mst.count() - mss.count() << endl;
}

int solve(unsigned int n, vector<int> &primes) {
    //vector<vector<int>> dp;
    //for (int y = 0; y <= primes.size(); ++y) {
    //vector<int> t(n+1, -1);
    //    dp.push_back(t);
    //}
    //dp[0][0] = 0;
    dp[0][0] = 1;

    for (int y = 1; y <= primes.size(); ++y) {
        int p = primes[y-1];
        for (int x = 0; x <= n; ++x) {
            if (x >= primes[y-1] && dp[y-1][x-primes[y-1]] >= 1)
                dp[y][x] = max(dp[y-1][x-primes[y-1]]+1, dp[y-1][x]);
            else
                dp[y][x] = dp[y-1][x];
        }
    }
    return dp[primes.size()][n] - 1;
}