import collections
class TreeNode:
   def __init__(self, data, left = None, right = None):
      self.data = data
      self.left = left
      self.right = right
def insert(temp,data):
   que = []
   que.append(temp)
   while (len(que)):
      temp = que[0]
      que.pop(0)
      if (not temp.left):
         if data is not None:
            temp.left = TreeNode(data)
         else:
            temp.left = TreeNode(0)
         break
      else:
         que.append(temp.left)
      if (not temp.right):
         if data is not None:
            temp.right = TreeNode(data)
         else:
            temp.right = TreeNode(0)
         break
      else:
         que.append(temp.right)
def make_tree(elements):
   Tree = TreeNode(elements[0])
   for element in elements[1:]:
      insert(Tree, element)
   return Tree
def search_node(root, element):
   if (root == None):
      return None
   if (root.data == element):
      return root
   res1 = search_node(root.left, element)
   if res1:
      return res1
   res2 = search_node(root.right, element)
   return res2
def print_tree(root):
   if root is not None:
      print_tree(root.left)
      print(root.data, end = ', ')
      print_tree(root.right)
def solve(root, node_list):
   nodes = []
   for elem in node_list:
      nodes.append(search_node(root, elem))
      nodes = set(nodes)
def fn(node):
   if not node:
      return node
   elif node in nodes:
      return node
      left, right = fn(node.left), fn(node.right)
      return node if left and right else left or right
   return fn(root)
root = make_tree([5, 3, 7, 2, 4, 6, 8])
print(solve(root, [6,8]).data)

make_tree([5, 3, 7, 2, 4, 6, 8]), [6, 8]

7