using System;

public class Program

{

    public static void Main()

    {

                {

            double[] arr = new double[4];

            Console.WriteLine("Enter values: ");

            for (int i = 0; i < arr.Length; i++)

            {

                arr[i]=double.Parse(Console.ReadLine());

            }

            if ((arr[3] - arr[2]) == (arr[2] - arr[1]))

            {

                double d = (arr[3] - arr[2]);

                double firstNextNumber = arr[3]+d;

                double secondNextNumber = firstNextNumber + d;

                Console.WriteLine("The values are an arithmetic series.");

                Console.WriteLine("Next 2 values would be: {0} , {1}",firstNextNumber,secondNextNumber);

            }

            else if ((arr[3] / arr[2]) == (arr[2] / arr[1]))

            {

                double q = (arr[3] / arr[2]);

                double firstNextNumber = arr[3] * q;

                double secondNextNumber = firstNextNumber * q;

                Console.WriteLine("The values are a geometric series.");

                Console.WriteLine("Next 2 values would be: {0} , {1}", firstNextNumber, secondNextNumber);

            }

            else

            {

                Console.WriteLine("The values are not an arithmetic series or a geometric series.");

            }

    }

    }

}