import java.util.*;
public class parking{
    public static void main(String[]args){
        Scanner sc=new Scanner(System.in);
        int hours=sc.nextInt();
        if(!sc.hasNextDouble()) {
            Ssytem.out.print("Invalid input");
            return;
        }
        double rate=sc.nextDouble();
        
        if(hours<0||hours>=24||rate<0){
            System.out.print("Invalid input");
        }
        else{
            System.out.printf("%.2f",hours*rate);
        }
    }
}