bloc_lst = []
def blocked_list(root):
    if root is None:
        return
    
    if root.left:
        if root.left.right:
            #print(root.left.right.info,end=" ")
            bloc_lst.append(root.left.right.info)
    
    if root.right:
        if root.right.left:
            #print(root.right.left.info,end=" ")
            bloc_lst.append(root.right.left.info)
    
    blocked_list(root.left)
    blocked_list(root.right)
    
from collections import defaultdict

def topView(root):
    if not root:
        return
    
    blocked_list(root)
    
    blocked_nodes = bloc_lst

    # Create a dictionary to store nodes at each horizontal distance from the root
    hd_map = defaultdict(list)

    # Create a queue for level-order traversal
    queue = [(root, 0)]  # Each element is a tuple (node, horizontal distance)

    while queue:
        node, hd = queue.pop(0)

        # Check if the node is not blocked
        if node.info not in blocked_nodes:
            hd_map[hd].append(node.info)

        if node.left:
            queue.append((node.left, hd - 1))
        if node.right:
            queue.append((node.right, hd + 1))

    # Print the top view nodes in order of horizontal distance
    for hd in sorted(hd_map):
        print(hd_map[hd][0], end=" ")