#include <iostream>
#include <algorithm>
#include <ctype.h>
#include <math.h>
using namespace std;


int main ()
{

long long x;
cin >> x;

long long happiness=0;
long long a,b,c;

a=x/500;
b=x%500;
c=b/5;

cout << a*1000+c*5 << endl;


	return 0;
}










#include<iostream>
#include<stdio.h>
#include<cmath>
using namespace std;
int main(){
    double x1,x2,y1,y2;
    cin >> x1 >> y1 >> x2 >> y2;
    cout << fixed << sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1)) << endl;
}
