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


int main ()  {
    ll n; cin >> n; 
    ll answer = 0, secondAnswer = 0; 
    if (n >= 500) {
        answer = n / 500; 
        ll a; 
        a = n % 500;
        secondAnswer = a / 5;  
    } 
    if (n < 500) {
        secondAnswer = n / 5; 
    }
    cout << answer * 1000 + secondAnswer * 5; 
    return 0;
}