using System;

namespace Ivanovi_s_Family
{
    class Program
    {
        static void Main(string[] args)
        {
            var budget = double.Parse(Console.ReadLine());
            var firstChild = double.Parse(Console.ReadLine());
            var secondChild = double.Parse(Console.ReadLine());
            var thirtChild = double.Parse(Console.ReadLine());
            var podaruci = firstChild + secondChild + thirtChild;
            var resto = budget - podaruci;
            var danak = (budget - podaruci) * 0.10;
            var darenie = resto - danak;
            Console.WriteLine($"{darenie:f2}");
        }
    }
}