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