using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        int?[] list = new int?[] { 1, 5, 3 };

        list = null;

        var res = list?.FirstOrDefault() == 2 ? list.FirstOrDefault()

            : list?.Count() >= 2 ? list?.Skip(1)?.FirstOrDefault()

                : list?.Skip(2)?.FirstOrDefault();

        Console.WriteLine("res = " + res);

        Console.ReadKey();

    }

}