#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h;
  while (cin >> n >> d >> h) {
    if (n < h + 1 || !(h <= d && d <= 2 * h) || (d == h && h == 1 && n != 2)) {
      cout << -1 << endl;
      continue;
    }
    for (int i = 2; i <= h + 1; ++i) {
      printf("%d %d\n", i - 1, i);
    }
    for (int i = h + 2; i <= n && i <= d + 1; ++i)
      printf("%d %d\n", (i == h + 2 ? 1 : i - 1), i);
    for (int i = d + 2; i <= n; ++i) printf("%d %d\n", h, i);
  }
  return 0;
}
