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

#define ll long long

void solve()
{
   ll n; cin>>n;
   ll m=n/500;
   ll o=n%500;
   cout<<(m*1000)+(o/5)*5<<endl;
   
}

int main()
{
    ll t=1;
   // cin>>t;
    while(t--) solve();
    return 0;
}