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

int abs(int a){
    if(a<0){
        return -1*a;
    }
    else return a;
}
int main(){
    int n;cin>>n;
    int count=0;
    while(n>=500){
        count+=1000;
        n-=500;
    }
    int a=n/5;count+=a*5;
    cout<<count;
}