#include <bits/stdc++.h>
const int INF = 0x3f3f3f3f;
const long double pi = acos(-1);
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  ;
  int n, d, h;
  cin >> n >> d >> h;
  if (d > 2 * h or (d == 1 and h == 1 and n > 2)) {
    cout << "-1"
         << "\n";
    return 0;
  }
  for (int i = 1; i <= h; i++) cout << i << " " << i + 1 << "\n";
  if (d != h) {
    int falta = n - 1 - h;
    if (falta > 0) {
      cout << 1 << " " << h + 2 << "\n";
      falta--;
    }
    for (int i = 2; i <= d - h; i++) {
      cout << h + i << " " << h + i + 1 << "\n";
      falta--;
      if (falta == 0) break;
    }
    int i = d + 2;
    while (falta > 0) {
      cout << 1 << " " << i << "\n";
      i++;
      falta--;
    }
  } else {
    int falta = n - 1 - h;
    int i = h + 2;
    while (falta > 0) {
      cout << 2 << " " << i << "\n";
      i++;
      falta--;
    }
  }
  return 0;
}
