use std::cmp::max;

trait TreeLike {
    fn height(&self) -> i32;
}

struct Tree {
    left: Option<Box<Tree>>,
    right: Option<Box<Tree>>,
    value: i32
}

impl TreeLike for Tree {

    fn height(&self) -> i32 {
        1 + max(self.left.height(), self.right.height())
    }
}

impl TreeLike for Option<Box<Tree>> {

    fn height(&self) -> i32 {
        match self {
            Some(ref tree) => tree.height(),
            None => 0,
        }
    }
}

fn main() {
    let child = Tree {
        left: None,
        right: None,
        value: 3,
    };
    let parent = Tree {
        left: Some(Box::new(child)),
        right: None,
        value: 2,
    };
    let a = parent.height().to_string();
    println!("{0}", a);
}