#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n, d, h;
  cin >> n >> d >> h;
  if (h < d / 2 + d % 2) {
    cout << -1 << endl;
    return 0;
  }
  if (d == 1 && n > 2) {
    cout << -1 << endl;
    return 0;
  } else {
    int x = 2;
    cout << 1 << " " << x << endl;
    int v = 2;
    int duph = h - 1;
    while (duph--) {
      cout << x << " " << x + 1 << endl;
      x++;
      v++;
    }
    x++;
    int z = d - h;
    if (z > 0) {
      z--;
      cout << 1 << " " << x << endl;
      v++;
    }
    while (z--) {
      cout << x << " " << x + 1 << endl;
      x++;
      v++;
    }
    int c = 1;
    if (h == d) c++;
    while (v < n) cout << c << " " << ++v << endl;
  }
  return 0;
}
