class Solution:

    def helper(self, root, depth):
        if root.left is None and root.right is None:
            if depth == 0:
                self.res_node = root
            if depth > self.maxdepth:
                self.maxdepth = depth
                self.res_node = root 

            return depth

        if root.left and root.right:
            leftMax = self.helper(root.left, depth + 1)
            rightMax = self.helper(root.right, depth + 1)

            if leftMax == rightMax:
                if leftMax >= self.maxdepth:
                    self.res_node = root
                    self.maxdepth = leftMax

            return max(leftMax, rightMax)

        elif root.left:
            return self.helper(root.left, depth + 1)
        else:
            return self.helper(root.right, depth + 1)

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

        self.maxdepth = 0
        self.res_node = None
        self.helper(root, 0)
        return self.res_node