import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        double money = scanner.nextDouble();
        if(money >= 5000) {
            System.out.printf("%.1f", money * 0.6);
        } else if(money >= 2000) {
            System.out.printf("%.1f", money * 0.7);
        } else if(money >= 500) {
            System.out.printf("%.1f", money * 0.8);
        } else if(money >= 100) {
            System.out.printf("%.1f", money * 0.9);
        } else if(money >= 0) {
            System.out.printf("%.1f", money);
        }
    }
}