For the resulting tree, print a list of all vertices that have two children, in ascending order.
Input
Enter a sequence of integers ending in zero. Zero itself is not included in the sequence. Build a tree according to this sequence.
Output
Print the answer to the problem.
Examples
| # |
Input |
Output |
| 1 |
7 3 2 1 9 5 4 6 8 0
|
3
5
7
|