Sets & Dictionaries Advanced - 4. Cities by Continent and Co

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Advanced
{
    class Program
    {
        static void Main(string[] args)
        {
            var cities = new Dictionary<string, Dictionary<string, List<string>>>();

            var number = int.Parse(Console.ReadLine());

            for (int i = 0; i < number; i++)
            {
                var input = Console.ReadLine().Split();

                var continent = input[0];
                var country = input[1];
                var city = input[2];

                if (!cities.ContainsKey(continent))
                {
                    cities[continent] = new Dictionary<string, List<string>>();
                }

                if (!cities[continent].ContainsKey(country))
                {
                    cities[continent][country] = new List<string>();
                }

                cities[continent][country].Add(city);
            }

            foreach (var continent in cities)
            {
                var continentName = continent.Key;
                Console.WriteLine($"{continentName}:");

                foreach (var country in continent.Value)
                {
                    var countryName = country.Key;
                    var citiesNames = country.Value;
                    Console.WriteLine($"{countryName} -> {string.Join(", ", citiesNames)}");
                }
            }
        }
    }
}