#include <bits/stdc++.h>
using std::cin;
using std::cout;
const int maxn = 1e5 + 5;
int n;
std::vector<int> num;
void printTree() {
  int cur = 0;
  for (int x : num) {
    int tmp = cur;
    cur += x;
    if (!tmp) continue;
    for (int y = tmp + 1; y <= cur; y++) printf("%d %d\n", tmp, y);
  }
}
int main() {
  cin >> n;
  if (n <= 5) {
    puts("-1");
  } else {
    num.push_back(1);
    if (n % 2 == 1) {
      num.push_back(4);
      for (int i = 0; i < n - 7; i++) num.push_back(1);
      num.push_back(2);
    } else {
      num.push_back(3);
      for (int i = 0; i < n - 6; i++) num.push_back(1);
      num.push_back(2);
    }
    printTree();
  }
  for (int i = 1; i < n; i++) {
    printf("%d %d\n", i, i + 1);
  }
  return 0;
}
