static void Main(string[] args)
{
Graph <string> graph = new Graph <string>();
var a = graph.AddVertice("a");
var b = graph.AddVertice("b");
var c = graph.AddVertice("c");
var d = graph.AddVertice("d");
graph.AddUndirectedEdge(a, b, 5);
graph.AddUndirectedEdge(b, c, 5);
graph.AddUndirectedEdge(c, d, 5);
graph.AddUndirectedEdge(d, a, 5);
graph.Print();
graph.Neighbors(b);
}
