using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var planets = new SortedList<int, string> {

            { 1, "Mercury" },

            { 2, "Venus" },

            { 3, "Earth" }

        };

        string value = string.Empty;

        planets.TryGetValue(3, out value);

        Console.WriteLine(value);

        // Or

        Console.WriteLine("--------------");

        if (planets.TryGetValue(4, out value)) // 4 is not in the list

            Console.WriteLine(value);

        else

            Console.WriteLine("Key not found");

    }

}