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 App {
    public static void main (String[] args) throws java.lang.Exception {
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        //reader = new BufferedReader(new FileReader(new File("C:\\Users\\Anjali\\Desktop\\projects\\HelloWorld\\src\\input.txt")));
		BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out));
        //writer = new BufferedWriter(new FileWriter(new File("C:\\Users\\Anjali\\Desktop\\projects\\HelloWorld\\src\\output.txt")));
		//int tests = Integer.parseInt(reader.readLine());
        int tests = 1;
		//StringBuilder sb = new StringBuilder(tests);
		while (tests-- > 0){
		    solve(reader, writer);
            writer.write("\n");
		}
		reader.close();
        writer.flush();
        writer.close();
    }

 
    static void solve(BufferedReader reader, BufferedWriter writer) throws  IOException {	
		int n = Integer.parseInt(reader.readLine());
		int[] arr = new int[101];
		if (n % 2 == 1) {
			writer.write("-1");
		} else {
			int i;
			for (i = 1; i <= n ; i ++) {
				if (i % 2 == 1) {
                    arr[i] = i + 1;
				} else {
					arr[i] = i - 1;
				}
			}
			for (i = 1; i < n; i++) {
				writer.write(arr[i] + " ");
			}
			writer.write(arr[i] + " ");
		}
    }
}