Create Tree Top View

Given a binary tree , print the nodes in left to right manner as visible from above the tree
Input Format

Level order input for the binary tree will be given.
Constraints

No of nodes in the tree can be less than or equal to 10^7
Output Format

A single line containing space separated integers representing the top view of the tree
Sample Input

1 2 3 4 5 6 -1 -1 -1 -1 -1 -1 -1

Sample Output

4 2 1 3

Explanation

The tree looks like

1
/ \
2 3
/ \ /
4 5 6

When viewed from the top , we would see the nodes 4, 2, 1 and 3.