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.*;
import java.lang.*;
import java.math.*;
import java.io.*;
import static java.lang.Math.*;
import static java.util.Arrays.*;
import static java.util.Collections.*;

public class P233A{
	Scanner sc=new Scanner(System.in);

	int n;

	void run(){
		n=sc.nextInt();
		solve();
	}

	void solve(){
		if(n%2==1){
			println("-1");
		}else{
			int[] a=new int[n];
			a[0]=2;
			a[1]=1;
			for(int i=2; i<n; i++){
				a[i]=n-i+2;
			}
			println(Arrays.toString(a).replaceAll(",", "").replace("[", "")
					.replace("]", ""));
		}
	}

	void println(String s){
		System.out.println(s);
	}

	void debug(Object... os){
		System.err.println(deepToString(os));
	}

	public static void main(String[] args){
		Locale.setDefault(Locale.US);
		new P233A().run();
	}
}