codeforces_622D. Optimal Number Permutation（构造）

D. Optimal Number Permutation

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

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 .

Input

The only line contains integer n (1 ≤ n ≤ 5·105).

Output

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

Examples

input

2

output

1 1 2 2

input

1

output

1 1

构造题，看出构造出di-(n-i)=0的数列就行，空缺的部分再扫一遍补上。

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