use std::cmp::Ordering::*;

type Link<T> = Option<Box<Node<T>>>;

#[derive(Debug)]
struct Node<T: Ord> {
    value: T,
    right: Link<T>,
    left: Link<T>,
}

impl<T: Ord> Node<T> {
    fn new(value: T) -> Self {
        Node {
            value: value,
            right: None,
            left: None
        }
    }
    fn add(&mut self, value: T) {
        let next = match self.value.cmp(&value) {
            Less => {
                &mut self.left
            },
            Greater => {
                &mut self.right
            },
            Equal => {panic!()},
        };
        if let &mut Some(ref mut n) = next {
            n.add(value);
        } else {
            *next = Some(Box::new(Node::new(value)));
        }

    }
}