using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        int ? [] items = {1, 3, 5, 7, 9, 13};

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

        {

            int ? previous = items.ElementAtOrDefault(i - 1);

            int ? current = items.ElementAtOrDefault(i);

            int ? next = items.ElementAtOrDefault(i + 1);

            Console.WriteLine("previous: {0} current: {1}, next: {2}", previous, current, next);

        }

    }

}