using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

​

namespace MVD

{

    public interface IMultiValueDictionary<K, V> : IEnumerable<KeyValuePair<K, V>>

    {

        bool Add(K key, V value);

        IEnumerable<V> Get(K key);

        bool Remove(K key);

        bool Remove(K key, V value);

    }

​

    public class MultiValueDictionary<K, V> : IMultiValueDictionary<K, V>

    {

        public bool Add(K key, V value)

        {

            throw new NotImplementedException();

        }

​

        public IEnumerable<V> Get(K key)

        {

            throw new NotImplementedException();

        }

​

        public bool Remove(K key)

        {

            throw new NotImplementedException();

        }

​

        public bool Remove(K key, V value)

        {

            throw new NotImplementedException();

        }

​

        public IEnumerator<KeyValuePair<K,V>> GetEnumerator()

        {

            throw new NotImplementedException();

        }

​

        IEnumerator IEnumerable.GetEnumerator() {

            return GetEnumerator();

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            var mvd = new MultiValueDictionary<int, string>();

            mvd.Add(1, "one");

            mvd.Add(2, "two");

            mvd.Add(2, "two_second");

            Console.WriteLine(mvd.Count()); // 3

            Console.WriteLine(mvd.Remove(3)); // false

            Console.WriteLine(mvd.Remove(1, "1")); // false

            Console.WriteLine(mvd.Remove(1, "one")); // true

            Console.WriteLine(mvd.Count()); // 2

            Console.WriteLine(mvd.Remove(2)); // true

            Console.WriteLine(mvd.Count()); // 0

        }

    }

}