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.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.HashSet;
import java.util.StringTokenizer;
import java.util.TreeSet;

public class Main {
    public static void main(String[] args) {
        final int n = nextInt();
        TreeSet<Integer> s = new TreeSet<>();
        for(int i = 1; i <= n; i++)
            s.add(i);

        try {
            int[] perm = new int[n + 1];
            for (int i = 1; i <= n; i++) {
                if (perm[i] == 0) {
                    int cur = s.pollFirst();
                    if (cur == i)
                        cur = s.pollFirst();

                    perm[i] = cur;
                    perm[perm[i]] = i;
                    s.remove(i);
                }
            }

            for(int i = 1; i <= n; i++)
                writer.print(perm[i] + " ");
        }catch (Exception e){
            writer.println(-1);
        }
        writer.close();
    }

    static PrintWriter writer = new PrintWriter(System.out);

    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    static StringTokenizer tokenizer = new StringTokenizer("");

    static String next() {
        while (!tokenizer.hasMoreTokens())
            try {
                tokenizer = new StringTokenizer(br.readLine());
            } catch (Exception e) {
                return null;
            }
        return tokenizer.nextToken();
    }

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

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

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