class Node: 
    """A binary tree node"""
    def __init__(self, data, left=None, right=None): 
        self.data = data 
        self.left = left 
        self.right = right 
  
  
def morris_traversal(root): 
    """Generator function for iterative inorder tree traversal"""
  
    current = root 
      
    while current is not None: 
          
        if current.left is None: 
            yield current.data 
            current = current.right 
        else: 
  
            # Find the inorder predecessor of current 
            pre = current.left 
            while pre.right is not None and pre.right is not current: 
                pre = pre.right 
  
            if pre.right is None: 
  
                # Make current as right child of its inorder predecessor 
                pre.right = current 
                current = current.left         
  
            else: 
                # Revert the changes made in the 'if' part to restore the  
                # original tree. i.e., fix the right child of predecessor 
                pre.right = None
                yield current.data 
                current = current.right 
              
# Driver program to test the above function 

root = Node(1, 
            right = Node(3), 
            left = Node(2, 
                      left = Node(4), 
                      right = Node(5) 
            ) 
       ) 
  
for v in morris_traversal(root): 
    print(v, end=' ')