using System;

namespace DogStore
{
    class DogStore
    {
        static void Main(string[] args)
        {
            var numberOfDogs = int.Parse(Console.ReadLine());
            var numberOfOtherAnimals = int.Parse(Console.ReadLine());

            var dogFoodPrice = 2.5d;
            var otherAnimalFoodPrice = 4;

            var moneyPaidForDogs = dogFoodPrice * numberOfDogs;
            var moneyPaidForOtherAnimals = otherAnimalFoodPrice * numberOfOtherAnimals;

            var result = Math.Round((moneyPaidForDogs + moneyPaidForOtherAnimals), 2).ToString("0.00");

            Console.WriteLine($"{result} lv.");
        }
    }
}