using System;

using System.Collections.Generic;   

public class Program

{

    public static void Main()

    {

        var cities = new Dictionary<string, string>(){

            {"UK", "London"},

            {"USA", "New York"},

            {"India", "New Delhi"},

            {"Wakanda", null},

        };

        foreach(var pair in cities) {

            try {

                ArgumentNullException.ThrowIfNull(pair.Value);

                Console.WriteLine("Country: " + pair.Key + ", City:" + pair.Value);

            } catch(System.ArgumentNullException) {

                Console.WriteLine("Could not find city for this country: " + pair.Key);

               // error handling code

            }

        }

    }

}