/*import java.util.Scanner;
import java.text.DecimalFormat;

public class ParkingFeeCalculator {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        try {
            if (!sc.hasNextInt()) {
                System.out.println("Invalid input");
                return;
            }
            int hoursParked = sc.nextInt();
            
            if (!sc.hasNextFloat()) {
                System.out.println("Invalid input");
                return;
            }
            float hourlyRate = sc.nextFloat();
            
            if (hoursParked < 0 || hourlyRate < 0) {
                System.out.println("Invalid input");
                return;
            }

            float totalFee = hoursParked * hourlyRate;

            DecimalFormat df = new DecimalFormat("0.00");
            System.out.println(df.format(totalFee));

        } catch (Exception e) {
            System.out.println("Invalid input");
        } finally {
            sc.close();
        }
    }
}*/

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        if (!sc.hasNextInt()) {
            System.out.println("Invalid input");
            return;
        }
        int hoursParked = sc.nextInt();

        if (!sc.hasNextDouble()) {  
            System.out.println("Invalid input");
            return;
        }
        float hourlyRate = sc.nextFloat();
        if(hoursParked<0 || hourlyRate<0 )
        {
            System.out.println("Invalid input");
            return;
        }
        if (hoursParked < 0 || hoursParked > 24 || hourlyRate < -10 || hourlyRate > 10) {
            System.out.println("Invalid input");
            return;
        }
        float totalFee = hoursParked * hourlyRate;
        System.out.printf("%.2f", totalFee);
    }
}