package src;

import java.util.*;
class C{
	static Scanner s = new Scanner(System.in);
	public static void main(String[] args) {
		int c=s.nextInt(),d=s.nextInt();
		if(c*5<=2*d)
			System.out.printf("%.10f",c*3500.0);
		else if(3*d<=c)
			System.out.printf("%.10f",d*4000.0);
		else
			System.out.printf("%.10f",(c*6000+d*34000)/13.0);
	}
}