Find the middle element when the numbers in an n \times n multiplication table are sorted in increasing order. It is assumed that n is odd. For example, the 3 \times 3 multiplication table is as follows:

The numbers in increasing order are [1,2,2,3,3,4,6,6,9], so the answer is 3. Input The only input line has an integer n. Output Print one integer: the answer to the task. Constraints

1 \le n < 10^6

Example Input: 3

Output: 3