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.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Tushar Paliwal
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        APerfectPermutation solver = new APerfectPermutation();
        solver.solve(1, in, out);
        out.close();
    }

    static class APerfectPermutation {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int permute[] = new int[n + 1];
            for (int i = 1; i <= n; i++) {
                permute[i] = i;
            }

            if (n % 2 == 1) {
                out.print(-1);
                return;
            } else {
                for (int i = 1; i < n; i += 2) {
                    int temp = permute[i];
                    permute[i] = permute[i + 1];
                    permute[i + 1] = temp;
                }
                for (int i = 1; i <= n; i++) {
                    out.print(permute[i] + " ");
                }
            }
        }

    }
}