add graph

public void AddVertex(object vertex)
        {
            List<object> tmp = new List<object>();
            graph.Add(vertex, tmp);

            Console.WriteLine("Do you want to add outcomming vertices? ");
            string answer = Console.ReadLine();
            if (answer == "yes")
            {
                Console.WriteLine("Enter outcomming vertices: ");
                string[] outcomingVetices = Console.ReadLine().Split(' ');
                for (int i = 0; i < outcomingVetices.Length; i++)
                    tmp.Add(int.Parse(outcomingVetices[i]));
            }

            Console.WriteLine("Do you want to add incomming vertices? ");
            answer = Console.ReadLine();
            if (answer == "yes")
            {
                Console.WriteLine("Enter outcomming vertices: ");
                string[] outcomingVetices = Console.ReadLine().Split(' ');
                for (int i = 0; i < outcomingVetices.Length; i++)
                {
                    object vert = int.Parse(outcomingVetices[i]);
                    graph[vert].Add(vertex);
                }
            }
        }

        public void AddEdge(object firstVertex, object secondVertex)
        {
            graph[firstVertex].Add(secondVertex);
        }

        public void RemoveVertex(object vertex)
        {
            graph.Remove(vertex);
            foreach (var item in graph)
            {
                if (item.Value.Contains(vertex))
                    item.Value.Remove(vertex);
            }
        }

        public void RemoveEdge(object firstVertex, object secondVertex)
        {
            graph[firstVertex].Remove(secondVertex);
        }