# Definition for a binary tree node.

# class TreeNode:

# def __init__(self, x):

# self.val = x

# self.left = None

# self.right = None

class Solution:

def __init__(self):

self.total = 0

def convertBST(self, root: TreeNode) -> TreeNode:

if root is not None:

self.convertBST(root.right)

self.total += root.val

root.val = self.total

self.convertBST(root.left)

return root