#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int n, d, h;
  cin >> n >> d >> h;
  if (n <= d) {
    cout << -1;
    return 0;
  }
  if (h == 1 && d == 1) {
    if (n == 2)
      cout << 1 << " " << 2 << endl;
    else
      cout << -1;
    return 0;
  }
  if (h * 2 >= d) {
    for (int i = 1; i <= h; ++i) {
      cout << i << " " << i + 1 << endl;
    }
    int v = 1;
    int nextv = h + 2;
    for (int i = 1; i <= d - h; ++i) {
      cout << v << " " << nextv << endl;
      v = nextv++;
    }
    v = 1;
    if (d == h) v = 2;
    for (int i = 1; i < n - d; ++i) {
      cout << v << " " << nextv << endl;
      nextv++;
    }
  } else
    cout << -1;
  return 0;
}
