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.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
/**
 *
 * @author Trung Pham
 */
public class Code {

    public static void main(String[] args) {
        try {
            BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
            int n = Integer.parseInt(in.readLine());
            if (n % 2 != 0) {
                System.out.println(-1);
                return;
            }
            System.out.print(2);

            for (int i = 1; i < n; i++) {
                if (i % 2 != 0) {
                    System.out.print(" " + i);
                } else {
                    System.out.print(" " + (i + 2));
                }
            }
        } catch (Exception ex) {
            Logger.getLogger(Code.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}