// editor2
import java.util.Scanner;
abstract class vehicle{
   abstract void car(float days, float price); 
   abstract void bike(float days, float price); 
   
}
class rent extends vehicle{
    @Override
    void car(float days, float price){
        days*=price;
        System.out.printf("$"+"%.2f",total);
    }
    @Override
    void bike(float days, float price){
        float total=days*price;
        System.out.printf("$"+"%.2f\n"+total);
    }
    
    
    
    
}
public class main{
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        rent r=new rent();
        
        String type=sc.nextLine();
        float days=sc.nextFloat();
        float price=sc.nextFloat();
        if(type.equals("car")){
            if(price>0)
            r.car(days,price);
            else
            System.out.println("Invalid input");
            
        }
        else if(type.equals("bike")){
            if(price>0)
            r.bike(days,price);
            else
            System.out.println("Invalid input");
        }
        else
        System.out.println("Invalid input");
        
    }
}