Middle Ex/Black Flag

using System;
using System.Linq;
using System.Collections.Generic;

namespace fundamental14
{
    class MainClass
    {
        public static void Main()
        {
            int day = int.Parse(Console.ReadLine());
            double pirate = double.Parse(Console.ReadLine());
            double grab = double.Parse(Console.ReadLine());
            double sum = 0;

            for (int i = 1; i <= day; i++)
            {

                sum += pirate;

                if (i % 3 == 0)
                {
                    sum += pirate / 2;
                }
                if (i % 5 == 0)
                {

                    sum -= sum * 0.3;
                }
            }

            if (sum >= grab)
            {
                Console.WriteLine($"Ahoy! {sum:f2} plunder gained.");
            }
            else
            {
                Console.WriteLine("Collected only {0:f2}% of the plunder.", (sum/grab)*100);
            }

        }
    }
}