#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, i, x, d, h, y = 2, val = -1, ans = 0;
  cin >> n >> d >> h;
  x = d - h;
  if (d > 2 * h || (d == h && h == 1 && n > 2)) {
    cout << -1 << "\n";
    return 0;
  }
  while (h--) {
    cout << y - 1 << " " << y;
    cout << "\n";
    y++;
  }
  for (i = 0; i < x; i++) {
    if (i == 0) {
      d = 1;
      cout << 1 << " " << y << "\n";
    } else {
      cout << y - 1 << " " << y << "\n";
      d = y - 1;
    }
    y++;
  }
  for (i = y; i <= n; i++) cout << d << " " << i << "\n";
  return 0;
}
