using System;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        int totalPages = 4;

        for (int currentPage = 1; currentPage <= totalPages; currentPage++)

        {

            Console.Write($"-> {currentPage} [{GetFirstPage(currentPage, totalPages)}] ~ [{GetLastPage(1, totalPages)}], total: {totalPages}\n");

        }

    }

​

    public static int GetLastPage(int currentPage, int totalPages)

    { 

        return (currentPage + 2 < totalPages ? Math.Max(currentPage, Math.Min(totalPages, 5)) : totalPages);

    }

​

    public static int GetFirstPage(int currentPage, int totalPages)

    {

        return (currentPage - 2 < 1 ? Math.Min(currentPage, 1) : currentPage - 2);

    }

}