class TreeNode(object):
	"""docstring for 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
        return max(self.TreeDepth(pRoot.left),self.TreeDepth(pRoot.right))+1