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

class Solution:
    def treeDepth(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        def func(root):
            if root:
                return max(func(root.left),func(root.right))+1
            return 0
        x=func(root)
        return x