static Node A_Star(Node root)
        {
            var goal = new Node(-1, Goal);

            Open.Add(root);
            while (Open.Count != 0)
            {
                var node = Open.First();
                Closed.Add(node);
                Open.RemoveAt(0);
                if (node.Equals(goal))
                {
                    return(node);
                }

                foreach (var child in node.GenerateChildren())
                {
                    var nodeInOpen   = Open.Where(x => x.Equals(child)).FirstOrDefault();
                    var nodeInClosed = Closed.Where(x => x.Equals(child)).FirstOrDefault();


                    if (child.Equals(goal))
                    {
                        return(child);
                    }

                    if (nodeInOpen != null)
                    {
                        if (nodeInOpen.Level > child.Level)
                        {
                            Open.Remove(nodeInOpen);
                            Open.Add(child);
                        }
                    }
                    else if (nodeInClosed != null)
                    {
                        if (nodeInClosed.Level > child.Level)
                        {
                            Closed.Remove(nodeInClosed);
                            Open.Add(child);
                        }
                    }
                    else
                    {
                        Open.Add(child);
                    }
                }
                Open.Sort((a, b) => a.FScore.CompareTo(b.FScore));
                //Open= Open.OrderBy(x => x.FScore).ToList();
            }
            Console.WriteLine("Unsolvable problem");
            return(null);
        }