static void Main(string[] args)
{
BST tree = new BST();
Node A = new Node();
Node B = new Node();
Node C = new Node();
Node D = new Node();
Node E = new Node();
Node F = new Node();
tree.Insert(A, 9);
tree.Insert(B, 7);
tree.Insert(C, 10);
tree.Insert(D, 6);
tree.Insert(E, 11);
tree.Insert(F, 1);
tree.PrintTree(A);
}