Smart Lili

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace issue14LiliPodaruk
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            // age of Lili
            double Price = double.Parse(Console.ReadLine());//cena na  ureda
            double ToyPrice =double.Parse(Console.ReadLine());//cena na edinichna igrachka
            double gift = 0; //edinichen podaruk suma
            double totalsum = 0; // obshti pari
            double toy=0; //obsto igrachki
            for(int i=1;i<=n;i++)
            {
                // for even year!
                if(i%2==0)
                {
                   gift=(((10*i)/2)-1);
                   totalsum+=gift;

                }
                 else
                {

                    toy +=1;

                }

            }
            double Toysum = toy * ToyPrice;
            double Total = Toysum + totalsum;

            if (Total >= Price)
            {
                Console.WriteLine("Yes! {0:f2}",Math.Abs(Total-Price));
            }
            else
            {
                Console.WriteLine("No!{0:f2}",Math.Abs(Price-Total));
            }












        }
    }
}