import java.io.*;
import java.util.*;

public class Main {

    private static void solve(InputReader in, OutputWriter out) {
        int n = in.nextInt();

        if (n < 6) {
            out.println(-1);
        } else {
            int m = (n - 2);
            for (int i = 2; i <= m; i++) {
                out.println("1 " + i);
            }
            out.println(m + " " + (m + 1));
            out.println(m + " " + (m + 2));
        }

        for (int i = 2; i <= n; i++) {
            out.println("1 " + i);
        }
    }

    private static void shuffleArray(int[] array) {
        int index;
        Random random = new Random();
        for (int i = array.length - 1; i > 0; i--) {
            index = random.nextInt(i + 1);
            if (index != i) {
                array[index] ^= array[i];
                array[i] ^= array[index];
                array[index] ^= array[i];
            }
        }
    }

    public static void main(String[] args) {
        InputReader in = new InputReader(System.in);
        OutputWriter out = new OutputWriter(System.out);
        solve(in, out);
        in.close();
        out.close();
    }

    private static class InputReader {
        private BufferedReader br;
        private StringTokenizer st;

        InputReader(InputStream is) {
            br = new BufferedReader(new InputStreamReader(is));
            st = null;
        }

        String nextLine() {
            String line = null;
            try {
                line = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return line;
        }

        String next() {
            while (st == null || !st.hasMoreTokens()) {
                String line = nextLine();
                if (line == null) return null;
                st = new StringTokenizer(line);
            }
            return st.nextToken();
        }

        byte nextByte() {
            return Byte.parseByte(next());
        }

        short nextShort() {
           ... Which one is the correct time complexity of the code snippet: constant, linear, quadratic, cubic, log(n), nlog(n) or NP-hard?