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.ArrayList;
import java.util.Scanner;

public class PerfectPermutation {
    public static void main(String[] args){
        Scanner kbd = new Scanner(System.in);
        int permutationValue = Integer.parseInt(kbd.nextLine());
        String permutationString = "";
        if(permutationValue < 2 || permutationValue%2 != 0){
            System.out.println("-1");
        }else{
            ArrayList permutationValues = new ArrayList();
            for(int i = 1; i <= permutationValue; i++){
                permutationValues.add(i);
            }
            
            int toggle = 1;

            for(int i = 0; i < permutationValue; i++){
               if(toggle == 1){
                   permutationString += permutationValues.get(i + 1) + " ";
                   toggle = 2;
               }else{
                   permutationString += permutationValues.get(i - 1) + " ";
                   toggle = 1;
               }
            }
        }
        
        System.out.println(permutationString);
    }
}