import java.util.Scanner;
class YunFei{
public static void main(String args[]){
System.out.println("请输入货物的重量和路程");
Scanner sc=new Scanner(System.in);
double b=sc.nextDouble();
double a=sc.nextDouble();
double t;
if(100<=b&&b<300) t=0.90*a*b;
if(300<=b&&b<500) t=0.80*a*b;
if(500<=b&&b<1000) t=0.70*a*b;
if(b<100) t=1.00*a*b;
if(b>=1000) t=0.60*a*b;System.out.println(t);
}
}