# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class BSTIterator(object):
    res = []
    index = 0

    def __init__(self, root):
        """
        :type root: TreeNode
        """
        stack = []
        while True:
            while root:
                stack.append(root)
                root = root.left
            if not stack:
                break
            root = stack.pop()
            self.res.append(root.val)
            root = root.right

    def next(self):
        """
        @return the next smallest number
        :rtype: int
        """
        if self.hasNext():
            self.index += 1
            return self.res[self.index - 1]
        
    def hasNext(self):
        """
        @return whether we have a next smallest number
        :rtype: bool
        """
        if self.index != len(self.res):
            return True
        return False
        


# Your BSTIterator object will be instantiated and called as such:
# obj = BSTIterator(root)
# param_1 = obj.next()
# param_2 = obj.hasNext()