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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

    public static void lexicoPermute(int n) {
        //1: Declare and initialize variables
        int permutation[] = new int[n];
        int temp;

        //2: Fill the array with numbers, even first, then odd
        for (int i = 1; i < n; i += 2) {
            permutation[i] = i;
            permutation[i - 1] = i + 1;

        }

        //3: Switch the last two elements if the size is odd
        if (n % 2 != 0) {
            temp = permutation[n - 2];
            permutation[n - 2] = permutation[n - 1];
            permutation[n - 1] = temp;
            permutation[n - 2] = n;
        }

        //4: Print the result
        for (int i = 0; i < n; i++) {
            System.out.print(permutation[i] + " ");
        }

        System.out.println();

    }

    public static void main(String[] args) throws IOException {
        //1: Declare and initialize variables
        InputStreamReader reader = new InputStreamReader(System.in);
        BufferedReader in = new BufferedReader(reader);
        StringTokenizer st = new StringTokenizer(in.readLine());
        int permutationSize = Integer.parseInt(st.nextToken());

        //2: Generate a perfect permutation 
        if (permutationSize % 2 == 1) {
            System.out.println(-1);
        } else {
            lexicoPermute(permutationSize);
        }

    }
}