import java.util.*;
class Main{
    public static void main(String[]args){
        Scanner sc=new Scanner(System.in);
        String name=sc.nextLine();
        int quantity=sc.nextInt();
        double price=sc.nextDouble();
        if(quantity<0 && price<0){
            System.out.println("Invalid input");
            return;
        }
        if(1>name.length()<20){
            System.out.println("Invalid input");
            return;
        }
        double res=(int)quantity*price;
        System.out.printf("%.2f",res);
    }
}