using System;
namespace Pet_Shop
{
    class Program
    {
        static void Main(string[] args)
        {
                double myDog = double.Parse(Console.ReadLine());
                double neiDog = double.Parse(Console.ReadLine());
                double dogPrice = myDog * 2.50;
                double dogPriceNei = neiDog * 4;
                double total = dogPrice + dogPriceNei;
                Console.WriteLine($"{total :F1} lv.");
            }
        }
    }