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.*;

public class Binnum {

public static void main(String args[] ) throws Exception {
        
        Scanner scan = new Scanner(System.in);
        
        int n, count = 0, flag = 0;
        
        n = scan.nextInt();
        
        if( n%2 != 0)
        	flag = 1;
        
        int a[] = new int[n+1];
        
        if(flag == 1)
        	System.out.println("-1");
        else
        {
        	for(int i=1; i < n; i++)
        	{
        		if( i % 2 == 0)
        		{
        			a[ i-1 ]  = i; 
        		}
        		else 
        			a[ i+1 ] = i;
        	}
        
        	a[n-1] = n;
        
        	for(int i=1; i <= n; i++){
        		System.out.print(a[i]);
        		System.out.print(" ");
        	}
        }
	}
}