#include <bits/stdc++.h>
using namespace std;
int tree[100005];
int main() {
  int n, d, h;
  ios::sync_with_stdio(0);
  while (cin >> n >> d >> h) {
    if (n < h + 1 || !(h <= d && d <= 2 * h) || (d == h && h == 1 && n != 2)) {
      cout << -1 << "\n";
      continue;
    }
    int tmp = 1;
    for (int i = 1; i <= h; ++i) {
      cout << tmp << " " << tmp + 1 << "\n";
      ++tmp;
    }
    for (int i = 1; i <= d - h; ++i) {
      if (i == 1) {
        cout << 1 << " " << tmp + 1 << "\n";
      } else {
        cout << tmp << " " << tmp + 1 << "\n";
      }
      ++tmp;
    }
    while (tmp != n) {
      cout << h << " " << tmp + 1 << "\n";
      ++tmp;
    }
  }
  return 0;
}
