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:
//package CodeForce;


import java.util.*;
import java.io.*;
public class Round144A {

	
	//public static boolean[] b;
	//static int[] FF;
	//static int[] A;
	public static void main(String[] ard)  throws IOException
	{
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		PrintWriter pw=new PrintWriter(System.out);
		Integer n=Integer.valueOf(br.readLine().trim());
		if(n<=1)pw.println(-1);
		else
		{
			int[] P=new int[n+1];
			for(int i=1;i<=n;i++)P[i]=i;
			for(int i=1;i<=n-1;i+=2)
			{
				int temp=P[i];
				P[i]=i+1;
				P[i+1]=temp;
			}
			boolean b=true;
			for(int o=1;o<=n;o++)
			{
				if(P[o]==o){b=false;break;}
			}
			if(b)
			for(int i=1;i<=n;i++)pw.print(P[i]+" ");
			else
				pw.println(-1);
		}
		
		
		
	pw.close();
		
	}
	
	/*public static boolean[] Seive()
	{
		
		 b=new boolean[10000001];
		Arrays.fill(b, true);
		b[0]=false;
		b[1]=false;
		
		for(int i=2;i<=Math.sqrt(10000000);i++)
		{
			if(b[i])
			{
				
			 for(int j=i*i;j<=10000000;j+=i)
				{
					     b[j]=false;
					
				}
			}
			
		}
		return b;
	}*/
	
}