using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        INestedKeyValueCollection collection = new NestedKeyValueCollection();

​

        // Adding simple key-value pairs

        collection.Add("Name", "Sandeep");

        collection.Add("Age", 35);

​

        // Adding a nested dictionary

        var address = new NestedKeyValueCollection();

        address.Add("Street", "123 Main St");

        address.Add("City", "Springfield");

        address.Add("Zip", "12345");

​

        collection.Add("Address", address);

​

        // Accessing values

        Console.WriteLine($"Name: {collection["Name"]}");

        Console.WriteLine($"Age: {collection["Age"]}");

​

        if (collection.TryGetValue("Address", out object addressObj) && addressObj is INestedKeyValueCollection addr)

        {

            Console.WriteLine("Address:");

            Console.WriteLine($"  Street: {addr["Street"]}");

            Console.WriteLine($"  City: {addr["City"]}");

            Console.WriteLine($"  Zip: {addr["Zip"]}");

        }

​

        // Removing a key

        collection.Remove("Age");

        Console.WriteLine($"Age after removal: {collection["Age"] ?? "Key not found"}");

    }

​

    public interface INestedKeyValueCollection

    {

        public void Add(string key, object value);

        public bool Remove(string key);

        public bool TryGetValue(string key, out object output);

        public bool ContainsKey(string key);

        public object this[string key] { get; set; }

    }

​

    public class NestedKeyValueCollection : INestedKeyValueCollection

    {

        private Dictionary<string, object> _store;

        public NestedKeyValueCollection()

        {

            _store = new Dictionary<string, object>();

        }

​

        public void Add(string key, object value)

        {

            if (!_store.ContainsKey(key))

            {

                _store.Add(key, value);

            }

        }

​

        public bool Remove(string key)

        {

            if (_store.ContainsKey(key))

            {

                return _store.Remove(key);

            }

​

            return false;

        }

​

        public bool ContainsKey(string key)

        {

            if (_store.ContainsKey(key))

            {

                return true;

            }

​

            return false;

        }

​

        public object this[string key]

        {

            get

            {

                if (_store.ContainsKey(key))

                {

                    return _store[key];

                }

                else

                    return null;

            }

​

            set

            {

                _store[key] = value;

            }

        }

​

        public bool TryGetValue(string key, out object value)

        {

            return _store.TryGetValue(key, out value);

        }

    }

}