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.Arrays;
import java.util.Scanner;


public class Main {
    public static long gcd ( long a, long b ) {
          if ( a==0 ) return b;
          return gcd(b%a,a);
        }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
Scanner s = new Scanner (System.in);

int i,j,T=s.nextInt();
if (T%2!=0)
{
    System.out.println(-1);
    return;
}

i=2;
j=1;
while (i<=T)
{
    if (i!=T)
    System.out.print(i+" "+j+" ");
    else
        System.out.println(i+" "+j);
    i+=2;
    j+=2;
}


    }
}