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 Main{
        public static void main(String[] args) {
            Scanner in=new Scanner(System.in);
            int num=in.nextInt();
            int ar[]=new int[num];
            if(num%2==0){
                for (int i = 0; i <num; i++) {
                ar[i]=i+1;
            }
            for (int i = 0; i < num-1; i=i+2) {
                int swap=ar[i];
                ar[i]=ar[i+1];
                ar[i+1]=swap;
            }
            for (int i = 0; i <num; i++) {
                System.out.print(ar[i]+" ");
            }
            System.out.println("");
            }
            else{
                System.out.println("-1");
            }
        }
    }