using System;

public class Program

    {

​

        public static void InputArr(int[] a)

        {

            a[0] = 2;

            a[1]=-4;

            for (int i = 0; i < a.Length-2; i+=2)

                a[i + 2] = a[i] + 4;

            for (int i = 1; i < a.Length-1; i+=2)

                a[i + 2] = a[i]-4;

        }

​

​

       public static void Main(string[] args)

        {

            int[] a = new int[10];

            InputArr(a);

           Console.Write("array a: ");

            for (int i = 0; i < 10; i++)

            {

                Console.Write(a[i] + "\t");

            }

            Console.WriteLine();

        }

    }

​