Chemistry

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

namespace Chemistry
{
    public class Node<T>
    {
        private T value;

        public T Value
        {
            get
            {
                return this.value;
            }
            set
            {
                this.value = value;
            }
        }


        public Node(T value)
        {
            this.Value = value;
        }

        public override string ToString()
        {
            return this.value.ToString();
        }

        public override bool Equals(object obj)
        {
            Node<T> n = obj as Node<T>;
            return n.Value.Equals(this.Value);
        }

        public override int GetHashCode()
        {
            return this.value.GetHashCode();
        }
    }

    class Graph<T>
    {
        private Dictionary<Node<T>, List<Node<T>>> adj;

        public Graph()
        {
            adj = new Dictionary<Node<T>, List<Node<T>>>();
        }

        public void AddNode(Node<T> node)
        {
            if (!this.adj.ContainsKey(node))
            {
                this.adj[node] = new List<Node<T>>();
            }
        }

        public void AddEdge(Node<T> source, Node<T> dest)
        {
            if (!adj.ContainsKey(source))
            {
                throw new ArgumentException("Nodes not existing!");
            }
            if (adj[source].Contains(dest))
            {
                return;
                //throw new Exception("Edge already exist!");
            }
            adj[source].Add(dest);
        }

        public bool HasEdge(Node<T> src, Node<T> dest)
        {
            if (!adj.ContainsKey(src))
            {
                return false;
            }
            if (!adj[src].Contains(dest))
            {
                return false;
            }
            return true;
        }

    }
    class Program
    {
        static void Main(string[] args)
        {
            Graph<string> chemistry = new Graph<string>();
            while (true)
            {
                string input = Console.ReadLine();
                if (input == "end") break;
                string[] el = input.Split(' ').ToArray();
                Node<string> n1 = new Node<string>(el[0]);
                Node<string> n2 = new Node<string>(el[1]);
                chemistry.AddNode(n1);
                chemistry.AddNode(n2);
                chemistry.AddEdge(n1, n2);
            }
            while (true)
            {
                string input = Console.ReadLine();
                if (input == "end") break;
                string[] el = input.Split('-').ToArray();
                string[] el2 = el[1].Split(',').ToArray();
                Node<string> n1 = new Node<string>(el[0]);
                foreach (var item in el2)
                {
                    Node<string> n2 = new Node<string>(item);
                    if (chemistry.HasEdge(n1, n2))
                    {
                        Console.WriteLine($"{el[0]}-{item}");
                    }
                }
            }
        }
    }
}