Problem: A permutation is a sequence of integers p1, p2, ..., pn, consisting of n distinct positive integers, each of them doesn't exceed n. Let's denote the i-th element of permutation p as pi. We'll call number n the size of permutation p1, p2, ..., pn.

Nickolas adores permutations. He likes some permutations more than the others. He calls such permutations perfect. A perfect permutation is such permutation p that for any i (1 ≤ i ≤ n) (n is the permutation size) the following equations hold ppi = i and pi ≠ i. Nickolas asks you to print any perfect permutation of size n for the given n.

Input

A single line contains a single integer n (1 ≤ n ≤ 100) — the permutation size.

Output

If a perfect permutation of size n doesn't exist, print a single integer -1. Otherwise print n distinct integers from 1 to n, p1, p2, ..., pn — permutation p, that is perfect. Separate printed numbers by whitespaces.

Examples

Input

1


Output

-1


Input

2


Output

2 1 


Input

4


Output

2 1 4 3 

Solution (in JAVA):

Solution:

import java.util.Scanner;

public class A1 {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt(); //max 100
        //local variable here
        if (n%2 != 0) {
            System.out.println("-1");
        } else if (n % 2 == 0) {
            boolean flag = false;
            for (int i = 1; i <= n; i++) {
                if (flag) {
                    System.out.print(i - 1 + " ");
                    flag = !flag;
                } else {
                    System.out.print(i + 1 + " ");
                    flag = !flag;
                }
            }
        } else {
            boolean flag = false;
            for (int i = 1; i <= n; i++) {
                if (i == n - 1) {
                    System.out.print(n + " ");
                } else if (i == n) {
                    System.out.print(n-2 + " ");
                } else if (flag) {
                    System.out.print(i - 1 + " ");
                    flag = !flag;
                } else {
                    System.out.print(i + 1 + " ");
                    flag = !flag;
                }
            }
        }

    }
    //other method here
}