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.util.*;
import java.math.*;
import java.io.*;
import java.math.BigInteger;
public class Solution{
	 static class FastReader { 
	        BufferedReader br; 
	        StringTokenizer st; 
	        public FastReader() { 
	            br = new BufferedReader(new
	                     InputStreamReader(System.in)); 
	        } 
	        String next() { 
	            while (st == null || !st.hasMoreElements()) {
	                try{ 
	                    st = new StringTokenizer(br.readLine()); 
	                } catch (IOException  e) { 
	                    e.printStackTrace(); 
	                } 
	            } 
	            return st.nextToken(); 
	        } 
	        int nextInt() { 
	            return Integer.parseInt(next()); 
	        } 
	        long nextLong() { 
	            return Long.parseLong(next()); 
	        } 
	        double nextDouble() { 
	            return Double.parseDouble(next()); 
	        } 
	        String nextLine()  { 
	            String str = ""; 
	            try{ 
	                str = br.readLine(); 
	            }catch (IOException e) { 
	                e.printStackTrace(); 
	            } 
	            return str; 
	        } 
	 }
	 
	 static class round{
		 String s;
		 int score;
		 round(String s,int score){
			 this.s=s;
			 this.score=score;
		 }
	 }
	
	 
	public static void main(String[] args) throws Exception{
		FastReader ip=new FastReader();
		Solution obj=new Solution();
	    int n=ip.nextInt();
	    if(n%2!=0) {
	    	System.out.println(-1);
	    }else {
	    	int a=2;
	    	int k=0;
	    	while(true) {
	    		System.out.print(a+" ");
	    		k++;
	    		a--;
	    		if(k==2) {
	    			k=0;
	    			a=a+4;
	    		}
	    		if(a>n) {
	    			break;
	    		}
	    	}
	    }
	    
	   
	}
	
}