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.*;

import java.util.*;
import java.math.*;
import java.nio.charset.Charset;


public class Main{
    public static void main(String[] args) throws IOException {

         BufferedReader bf=new BufferedReader(new InputStreamReader(System.in));
       
         
    int n=Integer.parseInt(bf.readLine());
  StringBuffer out=new StringBuffer();
  if(n%2!=0){System.out.println("-1");}
  else{for(int i=n;i>=1;i--){out.append(i+" ");}
 
      System.out.println(out);}
    }
   
 
}