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