using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        SortedList<int, string> planets = new SortedList<int, string>();

        // Add item if key doesn’t exist in the collection

        planets[1] = "Mercury";

        planets[2] = "Venus";

        planets[3] = "Earth";

​

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

        foreach(var planet in planets)

            Console.WriteLine($"{planet.Key}, {planet.Value}");

        // Updated item if key exists

        planets[3] = "Earth - Updated";

​

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

        foreach(var planet in planets)

            Console.WriteLine($"{planet.Key}, {planet.Value}");

    }

}