import java.util.*;
abstract class Vehicle{
    abstract void price();
}
class Vehc extends Vehicle{
    String v;
    float day;
    float price;
    float tot;
    Vehc(String v,float day,float price){
        this.v=v;
        this.price=price;
        this.day=day;
    }

@Override
void price(){
    tot=day*price;
    System.out.printf("$"+"%.2f",tot);
}
}
public class Main{
    public static void main(String[]args){
        Scanner sc=new Scanner(System.in);
        String v=sc.nextLine();
        float day=sc.nextFloat();
        float price=sc.nextFloat();
        if(day<=0||price<=0){
            System.out.print("Invalid input");
            return;
        }
        if(v.equalsIgnoreCase("car")){
            obj.price();
        }else if(v.equalsIgnoreCase("bike")){
            obj.price();          
        }else{
            System.out.print("Invalid input");
        }
        Vehicle obj=new Vehc(v,day,price);
        obj.price();
    }
}