import java.util.Scanner;
public class Main {
    public static void main (String[] args) {
        Scanner MyScanner = new Scanner(System.in);
        int electricity = MyScanner.nextInt();
        double price;
        if(electricity <= 150){
            price =electricity * 0.4463;
            System.out.printf("%.1f",price);}
        if(electricity > 150 && electricity <= 400){
            price = electricity * 0.4663;
            System.out.printf("%.1f",price);}
        if(electricity > 400 ){
            price = electricity * 0.5663;
            System.out.printf("%.1f",price);}
    }
}