#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector<int> dp(n + 1, -1);
    vector<bool> tb(n + 1);
    dp[0] = 0;
    for(int i = 2, s = 0; i <= n; i++){
        if(tb[i])continue;
        for(int j = min(s, n - i); j >= 0; j--){
            if(dp[j] >= 0)dp[j + i] = max(dp[j + i], dp[j] + 1);
        }
        for(int j = i << 1; j <= n; j += i){
            tb[j] = true;
        }
        s += i;
    }
    cout << dp[n] << '\n';
}