import java.util.*;
public class pattern{
    public static void main(String[]args){
        Scanner sc=new Scanner(System.in);
        if(sc.hasnextInt()){
           int n=sc.nextInt();
           if(n<0){
               System.out.println("Invalid input");
           }
           int y=sc.nextInt();
           
           if(y>5){
               System.out.println("%.1f%n",(double)n*0.10);
           }
      else if(y>=2 && y<=5){
                System.out.println("%.1f%n",(double)n*0.05);
      }
       else{
            System.out.println("%.1f%n",(double)n*0);
       }
}
else{
           System.out.println("Invalid input");
       }
 
}
}