import java.util.*;
import java.math.BigDecimal;

class Main{
    public static void main(String[]args)throws Exception{
        Scanner sc = new Scanner(System.in);
        int a,b;
        a = sc.nextInt();
        b = sc.nextInt();
        BigDecimal biga = new BigDecimal(a);
        BigDecimal bigb = new BigDecimal(b);
        BigDecimal ei = new BigDecimal(0.8);
        BigDecimal two = new BigDecimal(0.2);
        BigDecimal fif = new BigDecimal(50);
        BigDecimal good = two.multiply(bigb);
        BigDecimal great = ei.add(good);
        BigDecimal yeah = fif.multiply(biga);
        BigDecimal amazing = yeah.divide(great,0,BigDecimal.ROUND_DOWN);
        BigDecimal answer = yeah.add(amazing);
        
        System.out.println(answer);
        
        
        
        
        
    }
}