#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int i, n, d, h;
  cin >> n >> d >> h;
  if (n >= d + 1 && d >= h + 1 && d <= 2 * h && h + 1 <= n && d >= 2) {
    for (i = 1; i <= h; i++) {
      cout << i << " " << i + 1 << endl;
    }
    i++;
    int f = 0;
    if (d - h > 0) {
      f = 1;
      cout << "1 " << i << endl;
      int temp = d - h - 1;
      for (int j = 1; j <= temp; j++, i++) cout << i << " " << i + 1 << endl;
    }
    if (f == 1) i++;
    for (int j = 1; j <= (n - d - 1); j++, i++) {
      cout << "1 " << i << endl;
    }
  } else if (n >= d + 1 && d == h && d <= 2 * h && h + 1 <= n && d >= 2) {
    for (i = 1; i <= h; i++) cout << i << " " << i + 1 << endl;
    i++;
    int k = i;
    for (int j = 1; j <= (n - k + 1); j++, i++) {
      cout << "2 " << i << endl;
    }
  } else if (d == 1 && n == 2 && h == 1) {
    cout << "1 "
         << "2" << endl;
  } else
    cout << "-1" << endl;
  return 0;
}
