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.io.PrintWriter;
import java.util.StringTokenizer;

public class A233_PerfectPermutation {
    public static void main(String[] args) {
        PrintWriter pw = new PrintWriter(System.out);
        int n = nextInt();
        if (n % 2 == 1)
            pw.println(-1);
        else {
            for (int i = 1; i < n + 1; i++)
                pw.print(i % 2 == 0 ? i - 1 + " " : i + 1 + " ");
        }
        pw.close();
    }

    private static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    private static StringTokenizer st;

    private static String next() {
        while (st == null || !st.hasMoreElements()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }

    private static String nextLine() {
        String str = "";
        try {
            str = br.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return str;
    }

    private static int nextInt() {
        return Integer.parseInt(next());
    }

    private static long nextLong() {
        return Long.parseLong(next());
    }

    private static double nextDouble() {
        return Double.parseDouble(next());
    }
}