import java.util.*;
public class ParkingFeeCalculator{
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        try{
            int hoursParked = sc.nextInt();
            double hourlyRate = sc.nextDouble();
            if(hoursParked < 0 || hoursParked > 24 || hourlyRate < -10 || hourlyRate > 10){
                System.out.println("Invalid input");
            }else{
                double totalFee = hoursParked * hourlyRate;
                System.out.print("%.2f\n", totalFee);
            }
        }catch (Exception e){
            System.out.println("Invalid input");
        }
    }
}