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.*;
    import java.util.*;



    public class Cf233A {

        public static void main(String args[]) throws IOException
        {
            InputReader in = new InputReader(System.in);
            PrintWriter w = new PrintWriter(System.out);
            int n = in.nextInt();
            if(n%2 == 1) w.println("-1");
            else {
                for(int i = n; i >= 1; i--) w.print(i + " ");
            }

            w.close();
        }

          static class InputReader {

                    private InputStream stream;
                    private byte[] buf = new byte[8192];
                    private int curChar, snumChars;
                    private SpaceCharFilter filter;

                    public InputReader(InputStream stream) {
                            this.stream = stream;
                    }

                    public int snext() {
                            if (snumChars == -1)
                                    throw new InputMismatchException();
                            if (curChar >= snumChars) {
                                    curChar = 0;
                                    try {
                                            snumChars = stream.read(buf);
                                    } catch (IOException e) {
                                            throw new InputMismatchException();
                                    }
                                    if (snumChars <= 0)
                                            return -1;
                            }
                            return buf[curChar++];
                    }

                    public int nextInt() {
                            int c = snext();
                            while (isSpaceChar(c))
                                    c = snext();
                            int sgn = 1;
                            if (c == '-') {
                                    sgn = -1;
                                    c = snext();
                            }
                            int res = 0;
                            do {
                                    if (c < '0' || c > '9')
                                            throw new InputMismatchException();
                                    res *= 10;
                                    res += c - '0';
                                    c = snext();
                            } while (!isSpaceChar(c));
                            return res * sgn;
                    }

                    public long nextLong() {
                            int c = snext();
                            while (isSpaceChar(c))
                                    c = snext();
                            int sgn = 1;
                            if (c == '-') {
                                    sgn = -1;
                                    c = snext();
                            }
                            long res = 0;
                            do {
                                    if (c < '0' || c > '9')
                                            throw new InputMismatchException();
                                    res *= 10;
                                    res += c - '0';
                                    c = snext();
                            } while (!isSpaceChar(c));
                            return res * sgn;
                    }

                    public int[] nextIntArray(int n) {
                            int a[] = new int[n];
                            for (int i = 0; i < n; i++)
                                    a[i] = nextInt();
                            return a;
                    }

                    public String readString() {
                            int c = snext();
                            while (isSpaceChar(c))
                                    c = snext();
                            StringBuilder res = new StringBuilder();
                            do {
                                    res.appendCodePoint(c);
                                    c = snext();
                            } while (!isSpaceChar(c));
                            return res.toString();
                    }

                    public boolean isSpaceChar(int c) {
                            if (filter != null)
                                    return filter.isSpaceChar(c);
                            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
                    }

                    public interface SpaceCharFilter {
                            public boolean isSpaceChar(int ch);
                    }
            }
    }