class BinarySearchTree
{
  static class TreeNode
  {
    String key;
    Object info;
    TreeNode left, right;
    TreeNode(String k, Object in, TreeNode l, TreeNode r)
    {
      key = k; info = in; left = l; right = r;
    }
    static TreeNode find(String k, TreeNode t);
    static TreeNode insert(String k, Object in, TreeNode t);
    static TreeNode remove(String k, TreeNode t);
    static String toString(TreeNode t);
  }
  TreeNode root;
  BinarySearchTree();
  void insert(String key, Object info);
  Object lookup(String key);
  void remove(String key);
  String toString();
}

void preorder(TreeNode root)
{
  if (root != null)
  {
    system.out.println(root.info);
    preorder(root.left);
    preorder(root.right);
  }
}

void inorder(TreeNode root)
{
  if (root != null)
  {
    inorder(root.left);
    system.out.println(root.info);
    inorder(root.right);
  }
}

void postorder(TreeNode root)
{
  if (root != null)
  {
    postorder(root.left);
    postorder(root.right);
    system.out.println(root.info);
  }
}