class Node:
    def __init__(self, data, left=None, right=None):
        self.data = data
        self.left = left
        self.right = right


class Bst:
    def __init__(self):
        self.head = None

    def check_bst():
        pass

class Node:
    def __init__(self, data, left=None, right=None):
        self.data = data
        self.left = left
        self.right = right


class Bst:
    def __init__(self):
        self.head = None

    def check_bst():
        pass
