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.*;
import java.math.BigInteger;
public class B {
	static PrintWriter out=new PrintWriter(System.out);
	public static void main(String[] args) throws Exception {
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		if(n%2==1)out.println(-1);
		else {
			for(int i=1;i<=n;i++) {
				if(i%2==1)out.print(i+1+" ");
				else out.print(i-1+" ");
			}
		}
		out.println();
		out.close();
	}
	
	static class Pair implements Comparable<Pair>{
		int x;
		int y;
		public Pair(int x,int y) {
			this.x=x;
			this.y=y;
		}
		public int compareTo(Pair o) {
			return (this.x!=o.x)?this.x-o.x:this.y-o.y;
		}
		public String toString() {
			return "("+this.x+","+this.y+")";
		}
		
	}
	static class Scanner {
		StringTokenizer st;
		BufferedReader br;
		public Scanner(InputStream s) {
			br = new BufferedReader(new InputStreamReader(s));
		}
		public Scanner(String file) throws FileNotFoundException {
			br = new BufferedReader(new FileReader(file));
		}
		public String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}
		public int nextInt() throws IOException {
			return Integer.parseInt(next());
		}
		public long nextLong() throws IOException {
			return Long.parseLong(next());
		}
		public String nextLine() throws IOException {
			return br.readLine();
		}
		public double nextDouble() throws IOException {
			return Double.parseDouble(next());
		}
		public boolean ready() throws IOException {
			return br.ready();
		}
		public int[] nextIntArr(int n) throws IOException{
			int arr[]=new int[n];
			for(int i=0;i<n;i++)arr[i]=nextInt();
			return arr;
		}
		public BigInteger BigInteger(String s) throws IOException{
			BigInteger a=new BigInteger(s);
			return a;
		}
	}
}