Given an increasing sequence of integers 1, 2, 4, 5, 7, 9, 10, 12, 14, 16, 17, ... It is formed as follows: one odd number is taken, then two even ones, then three odd ones, and so on . Output the N-th element of this sequence.
Input
One integer N (1 ≤ N ≤ 10
100).
Imprint
Print one integer - the N-th element of the sequence.
Examples
| # |
Input |
Output |
| 1 |
1 |
1 |
| 2 |
4 |
5 |