\begin{array}{c} \color{#FFFFFFff}{H}\color{#E7E7E7ff}{o}\color{#CFCFCFff}{r}\color{#B7B7B7ff}{i}\color{#9F9F9Fff}{z}\color{#878787ff}{o}\color{#6F6F6Fff}{n} \end{array} $\\$

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

int main() {
    freopen("CAU2.INP", "r", stdin);
    freopen("CAU2.OUT", "w", stdout);
    
    long long n, s = 0;
    cin >> n;


    if (n <= 15)
        s = n * 2000;
    else if (n <= 30) 
        s = 15 * 2000 + (n - 15) * 1500;
    else
        s = 15 * 2000 + 15 * 1500 + (n - 30) * 1000;

    cout << s;
}