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.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;


public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader r=new BufferedReader(new InputStreamReader(System.in));
        int n=Integer.parseInt(r.readLine());
        if(n%2==0){
        int p[]=new int[n+1];
        for (int i = 1; i <= n; i++) {
           p[i]=i%2==0?i-1:i+1;
           
        }
        BufferedWriter wr=new BufferedWriter(new OutputStreamWriter(System.out));
        for (int i = 1; i <= n; i++) {
            wr.write(p[i]+" ");
        
        }
         wr.newLine();
        wr.flush();}
        else System.out.println("-1");
    }
  
}