#include <bits/stdc++.h>
using namespace std;
int a[150001];
int main() {
  int n, d, h;
  cin >> n >> d >> h;
  if (h > n - 1 || d > 2 * h || d < h || h == 1 && d == 1 && n > 2) {
    cout << -1;
    return 0;
  }
  cout << 1 << " " << 2 << endl;
  for (int i = 2; i <= h; i++) {
    cout << i << " " << i + 1 << endl;
  }
  int j = h + 2;
  for (int i = 0; i < d - h - 1; i++, j++) {
    cout << j << " " << j + 1 << endl;
  }
  int l = j;
  if (d == h) {
    for (int i = l; i <= l + n && i <= n; i++) {
      cout << j - 2 << " " << i << endl;
    }
  } else {
    if (h + 2 <= n) cout << 1 << " " << h + 2 << endl;
    l = j + 1;
    for (int i = l; i <= l + n && i <= n; i++) {
      cout << 1 << " " << i << endl;
    }
  }
  return 0;
}
