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.PrintWriter;
import java.util.Scanner;

public class Main144A {

    Scanner in;
    PrintWriter out;

    void solve() {
        int n = in.nextInt();
        if (n % 2 != 0) {
            out.println(-1);
        } else {
            int a[] = new int[n + 1];
            for (int i = 1; i <= n; i++) {
                if (i % 2 != 0) {
                    a[i] = i + 1;
                }else{
                    a[i] = i-1;
                }
                out.print(a[i] + " ");
            }
        }
    }

    void run() {

        in = new Scanner(System.in);
        out = new PrintWriter(System.out);
        try {
            solve();
        } finally {
            out.close();
        }

    }

    public static void main(String[] args) {
        new Main144A().run();

    }

}