def smallestCommonAncestor(self, root, p, q):
    """
    :type root: TreeNode
    :type p: TreeNode
    :type q: TreeNode
    :rtype: TreeNode
    """
    smallest = None
    while root != None:
        if root.val > p.val and root.val > q.val:
            root = root.left
            smallest = None
        elif root.val < p.val and root.val < q.val:
            return root
        else:
            break
    return root

def lowestCommonAncestor(self, root, p, q):
    """
    :type root: TreeNode
    :type p: TreeNode
    :type q: TreeNode
    :rtype: TreeNode
    """
    if not root:
        return False
    if root == p or root == q:
        return root
    left = self.lowestCommonAncestor(root.left, p, q)
    right = self.lowestCommonAncestor(root.right, p, q)
    if left and right:
        return root
    return left or right