#include <bits/stdc++.h>
const long long OO = 1e16;
using namespace std;
string s;
int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  ;
  int n, h, d;
  cin >> n >> d >> h;
  if (n < d + 1 || d > 2 * h || d < h || (d == 1 && n > 2)) {
    cout << "-1";
    return 0;
  }
  n--;
  int j = (d == h) ? 2 : 1;
  while (n > 0) {
    for (int i = 1; i <= h; i++) {
      cout << i << " " << i + 1 << "\n";
      n--;
    }
    d = d - h;
    if (d > 0)
      h += 2;
    else
      h++;
    if (d > 0) {
      cout << "1 " << h << "\n";
      n--;
      d--;
    }
    for (int i = 1; i <= d; i++) {
      cout << h << " " << h + 1 << "\n";
      h++;
      n--;
    }
    h++;
    for (int i = 1; i <= n; i++) {
      cout << j << " " << h << "\n";
      h++;
    }
    n = 0;
  }
}
