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