using System.Collections;
using System.Collections.Generic;
public interface IMultiValueDictionary<K, V> : IEnumerable<KeyValuePair<K, V>>
bool Add(K key, V value);
IEnumerable<V> Get(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() {
public static void Main()
var mvd = new MultiValueDictionary<int, string>();
mvd.Add(2, "two_second");
Console.WriteLine(mvd.Count());
Console.WriteLine(mvd.Remove(3));
Console.WriteLine(mvd.Remove(1, "1"));
Console.WriteLine(mvd.Remove(1, "one"));
Console.WriteLine(mvd.Count());
Console.WriteLine(mvd.Remove(2));
Console.WriteLine(mvd.Count());