using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Arithmetic Sequence");

        Console.WriteLine("Write your sequence with atleast 3 numbers");

        int fs = Int32.Parse(Console.ReadLine());

        int ss = Int32.Parse(Console.ReadLine());

        int ts = Int32.Parse(Console.ReadLine());

        int d = ss - fs;

        int d1 = ts - ss;

        if (d == d1)

        {

            Console.WriteLine("Your sequence is Artitmetic");

            Console.WriteLine("Your sequence is " + fs + ", " + ss + ", " + ts + " .............");

            Console.WriteLine("Which term you want to find in your sequence");

            int nomnom = Int32.Parse(Console.ReadLine());

            int termnomnom = fs + (nomnom - 1) * d;

            Console.WriteLine("The " + nomnom + " th term in your sequence is " + termnomnom + ".");

            int rando = nomnom/2 * (2*fs + (nomnom - 1) * d);

            Console.WriteLine("The sum of all " + nomnom + " terms is " + rando + ".");

        }

        else if (d     d1)

        {

            int r = ss/fs;

            int r1 = ts/ss;

            if (r == r1)

            {

                Console.WriteLine("Your sequence is Geometric");

                Console.WriteLine("Which term you want to find in your sequence");

                int nomnom = Int32.Parse(Console.ReadLine());

                double rnnr = fs * (Math.Pow(r, (nomnom -1)));

                Console.WriteLine("The " + nomnom + "th term in your sequence is " + rnnr + ".");

                double termnomnom = (fs * (Math.Pow(r,nomnom) - 1)) / (r - 1);

                Console.WriteLine("The sum of all " + nomnom + " terms is " + termnomnom  + ".");

            }

        }

        else

        {

            Console.WriteLine("Your sequence is neither Arithmetic not Geometric.");

        }

    }

}