class Node(object):
    def __init__(self, value, parent = None):
        self._value = value
        self._children = []
        self._parent = parent


    def get_value(self):
        return self._value

    def get_children(self):
        return self._children

    def get_parent(self):
        return self._parent

    def set_parent(self, parent_node):
        self._parent = parent_node

    def add_child(self, new_node):
        self._children.append(new_node)

    def is_leaf(self):
        if self._children == []:
            return True
        else:
            return False

    def is_root(self):
        if self._parent == None:
            return True
        else:
            return False

    def depth(self):
        if self.is_root() == False:
            return 1 + self._parent.depth()
        else:
            return 1

    def dfs(self):
        print self._value
        if self.is_leaf():
            pass
        else:
            for child in self._children:
                child.dfs()

    def height(self):
        tmp = []
        if self.is_leaf():
            return 1
        else:
            for child in self._children:
                tmp.append(child.height())
                return 1 + max(tmp)


class Tree(object):
    def __init__(self, root = Node(0)):
        self._root = root

    def add_node(self, node, new_node):
        node.add_child(new_node)
        new_node.set_parent(node)


    def height(self):
        return self._root.height()






if __name__ == '__main__':
    koren = Node(1)
    stablo = Tree(koren)
    n1 = Node(2)
    n2 = Node(3)
    n3 = Node(4)
    n4 = Node(5)
    stablo.add_node(koren, n1)
    stablo.add_node(koren,n2)
    stablo.add_node(n2,n3)
    stablo.add_node(n3,n4)
    print stablo.height()