#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
int main() {
	
	ios_base::sync_with_stdio(0); 
    cin.tie(0);                   
    cout.tie(0);
    ll n; cin >> n;
    ll x = n / 500;
    ll sum = x * 1LL * 1000;
    n = n % 500;
    n = n / 5;
    sum += n * 1LL * 5;
    cout << sum << '\n';
    
    return 0;
}