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