Generic Hash Map

HashMap.cs

using System;
using System.Collections.Generic;

namespace HashMapImplementation
{
    public class Program
    {
        public static void Main(string[] args)
        {
            int n = 5;
            var hashMap = new HashMap<string, string>(n);
            hashMap.Add("test1", "aint");
            hashMap.Add("test1", "no");
            hashMap.Add("test2", "thing");
            
            test(hashMap, "test1");
            test(hashMap, "test2");
            test(hashMap, "test3");
        }
        
        static void test(HashMap<string, string> hashMap, string key) {
            try {
                Console.WriteLine("hashMap[{0}] = {1}", key, hashMap.Get(key));    
            } catch(Exception e) {
                Console.WriteLine("Error: {0} for {1}", e.Message, key);
            }
        }
    }
    
    class HashMap<K, V> {
        
        List<List<Tuple<K, V>>> table;
        int N;
        
        public HashMap(int n) {
            table = new List<List<Tuple<K, V>>>();
            N = n;
            for(int i = 0; i < N; i++) {
                table.Add(new List<Tuple<K, V>>());
            }
        }
        
        public void Add(K key, V value) {
            int index = position(key);
            var bucket = table[index];
            
            foreach(var item in bucket) {
                if (EqualityComparer<K>.Default.Equals(item.Key, key)) {
                    item.Value = value;
                    return;
                }
            }
            
            bucket.Add(new Tuple<K, V>(key, value));
        }
        
        public V Get(K key) {
            int index = position(key);
            var bucket = table[index];
            
            foreach(var item in bucket) {
                if (EqualityComparer<K>.Default.Equals(item.Key, key)) {
                    return item.Value;
                }
            }
            
            throw new Exception("Key not found");
        }
        
        int position(K key) {
            return Math.Abs(key.GetHashCode()) % N;
        }
    }
    
    class Tuple<K, V> {
        public Tuple(K key, V value) {
            this.Key = key;
            this.Value = value;
        }
        
        public K Key { get; private set; }
        
        public V Value { get; set; }
    }
}