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 PerfectPermutation {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		if(n == 1) {
			System.out.println("-1");
		}else {
			int arr[] = new int[n];
			for(int i = 0 ; i < n ; i++)
				arr[i] = i + 1;
			int j = 0;
			while(j < n && j + 1 < n) {
				int temp = arr[j];
				arr[j] = arr[j + 1];
				arr[j + 1] = temp;
				j += 2;
			}
			if(arr[arr.length - 1] == n)
				System.out.println("-1");
			else {
				for(int e : arr) {
					System.out.print(e + " ");
				}
			}
		}
		sc.close();
	}

}