Description:
You have array a that contains all integers from 1 to n twice. You can arbitrary permute any numbers in a.
Let number i be in positions xi, yi (xi < yi) in the permuted array a. Let's define the value di = yi - xi — the distance between the positions of the number i. Permute the numbers in array a to minimize the value of the sum $$s = \sum_{i=1}^{n}(n-i) \cdot |d_i + i - n|$$.
Input Format:
The only line contains integer n (1 ≤ n ≤ 5·105).
Output Format:
Print 2n integers — the permuted array a that minimizes the value of the sum s.
Note:
None