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.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import javax.swing.plaf.synth.SynthSpinnerUI;

import java.util.Queue;
import java.util.Scanner;
import java.util.Set;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.TreeMap;

 
public class george
{
    static class Reader
    {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;
 
        public Reader()
        {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }
 
        public Reader(String file_name) throws IOException
        {
            din = new DataInputStream(new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }
 
        public String readLine() throws IOException
        {
            byte[] buf = new byte[64]; // line length
            int cnt = 0, c;
            while ((c = read()) != -1)
            {
                if (c == '\n')
                    break;
                buf[cnt++] = (byte) c;
            }
            return new String(buf, 0, cnt);
        }
 
        public int nextInt() throws IOException
        {
            int ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do
            {
                ret = ret * 10 + c - '0';
            }  while ((c = read()) >= '0' && c <= '9');
 
            if (neg)
                return -ret;
            return ret;
        }
 
        public long nextLong() throws IOException
        {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }
 
        public double nextDouble() throws IOException
        {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
 
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');
 
            if (c == '.')
            {
                while ((c = read()) >= '0' && c <= '9')
                {
                    ret += (c - '0') / (div *= 10);
                }
            }
 
            if (neg)
                return -ret;
            return ret;
        }
 
        private void fillBuffer() throws IOException
        {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }
 
        private byte read() throws IOException
        {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }
 
        public void close() throws IOException
        {
            if (din == null)
                return;
            din.close();
        }
    }
    static int min(int []arr,int n) {
    int min=arr[0],k=-1;
    for(int i=0;i<n;i++) {
    	if(min>arr[i]) {
    		k=arr[i];
    	}
    }
    return k;
    }
    static int max(int []arr,int n) {
        int max=arr[0],k=-1;
        for(int i=1;i<n;i++) {
        	if(arr[i]>max) 
        		k=arr[i];
        }
        return k;
        }
static long gcd(long a,long b) {
	if (b==0) return a;
	return gcd(b,a%b);
}
static long lcm(int a,int b) {

	return a*b/gcd(a,b);
}
static int tprime(int n) {
int a=1;
	for(int i=2;i<=n;i++) {
		if(n%i==0) {
			System.out.println(i);
			a++;
		}
	}
	return a;
}
static long fact(int n){    
	long fact1=1;  
	      
	  for(int i=1;i<=n;i++){    
	      fact1=fact1*i;    
	  }   
	  return fact1;
	 }    
static void calculateSpan(int price[], int n, int S[])
{
    
    Stack<Integer> st= new Stack<>();
    st.push(0); 
    
    S[0] = 1;
    for (int i = 1; i < n; i++)
    {
        while (!st.empty() && price[st.peek()] <= price[i])
            st.pop();
        S[i] = (st.empty())? (i + 1) : (i - st.peek());
 
       
        st.push(i);
    }
}
 
static void printArray(int arr[],int n)
{
	for(int i=0;i<n;i++) {
    System.out.print(arr[i]+" ");
    }
	System.out.println();
}
 
    public static void main(String[] args) throws IOException
    {
        Reader s=new Reader();
       int n=s.nextInt();
       if (n % 2 == 1)
       {
           System.out.print("-1");
       }
       else
       {
           System.out.print("2 1");
           for (int i = 3; i < n; i += 2)
           {
               System.out.print(" "+(i+1)+ " " + i);;
           }
       }
    }	
}