text: class Node():
  
      def __init__(self, val):
          self.val = val
          self.right = None
          self.left = None
  
  
  def merge(t1, t2):
      if not t1:
          return t2
      if not t2:
          return t1
      t1.val = t1.val + t2.val
      t1.left = merge(t1.left, t2.left)
      t2.right = merge(t1.right, t2.right)
      return t1
  
  
  