# -*- coding:utf-8 -*-
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def TreeDepth(self, pRoot):
# write code here
if not pRoot: return 0
queue=[pRoot]
node=pRoot
count=0
while queue:
nodes=[]
while queue:
node=queue.pop()
#print(out)
if node.right:nodes.append(node.right)
if node.left:nodes.append(node.left)
count+=1
queue=nodes
return count