12. Clever Lily

using System;

namespace Clever Lily
{
    class Program
    {
        static void Main(string[] args)
        {
            int age = int.Parse(Console.ReadLine());
            double priceWashing = double.Parse(Console.ReadLine());
            int priceToy = int.Parse(Console.ReadLine());
            double money = 0;
            int toys = 0;
            double sum = 0;
            for (int i = 1; i <= age; i++)
            {
                if (i % 2 == 0)
                {
                    money += 5 * i - 1;
                }
                else
                {
                    toys++;
                }
            }
            sum = toys * priceToy + money;
            if (priceWashing > sum)
            {
                Console.WriteLine($"No! {priceWashing- sum:F2}");
            }
            else
            {
                Console.WriteLine($"Yes! {sum - priceWashing:F2}");
            }
        }
    }
}