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 \lt 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 .

The only line contains integer n (1 \le n \le 5 \cdot 105).

Print 2n integers - the permuted array a that minimizes the value of the sum s.