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.*;

public class solver {
    public static void main(String args[]) throws Exception{
        InputStreamReader r=new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(r);

        int n = Integer.parseInt(br.readLine());
        int i;
        if(n%2 == 1){
            System.out.print(-1);
        }
        else {
            i = 1;
            int o,e;
            while (i<n){
                o = i;
                e = i + 1;
                i += 2;
                System.out.print(e + " ");
                System.out.print(o + " ");
            }
        }
    }
}