using System;

namespace ImgurLinkConverter
{
    class Program
    {
        static void Main(string[] args)
        {
            //Console.Write("Input imgur link: ");
            //string link = Console.ReadLine();
            //Console.Write(ConvertLink(link));
            Console.Write(ConvertLink());
            Console.ReadKey();
        }

        private static string ConvertLink(string link)
        {
            if (
                !link.Contains("/a/") &&
                link.Contains("https://i...content-available-to-author-only...r.com/")
                )
            {
                link = link.Insert(8, "i.");
                return link + ".png";
            }
                return "Invalid link";
        }

        private static string ConvertLink()
        {
            string link = "https://i...content-available-to-author-only...r.com/imSB81I";
            return ConvertLink(link);
        }
    }
}