import java.util.Scanner;

class Main {
	public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long X = sc.nextLong();
        
        System.out.println((X/500) *1000 + (X%500) /5 *5);



        
        }
	} import java.util.Scanner; Scanner java.util class Main {
	public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long X = sc.nextLong();
        
        System.out.println((X/500) *1000 + (X%500) /5 *5);



        
        }
	} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long X = sc.nextLong();
        
        System.out.println((X/500) *1000 + (X%500) /5 *5);



        
        } main {
        Scanner sc = new Scanner(System.in);
        long X = sc.nextLong();
        
        System.out.println((X/500) *1000 + (X%500) /5 *5);



        
        } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long X = sc.nextLong(); X sc.nextLong() sc.nextLong sc System.out.println((X/500) *1000 + (X%500) /5 *5) System.out.println System.out System System.out (X/500) *1000 + (X%500) /5 *5 (X/500) *1000 (X/500) X 500 1000 (X%500) /5 *5 (X%500) /5 (X%500) X 500 5 5 String[] args args
import java.util.Scanner;

class Main {
	public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long X = sc.nextLong();
        
        System.out.println((X/500) *1000 + (X%500) /5 *5);



        
        }
	}
