#include <bits/stdc++.h>
using namespace std;
const int N = 100010;
int n, d, h;
vector<int> tree[N];
int get_height(int node = 0) {
  int height = 0;
  for (int i = 0; i < (int)tree[node].size(); i++)
    height = max(height, 1 + get_height(tree[node][i]));
  return height;
}
int main(void) {
  cin >> n >> d >> h;
  for (int i = 0; i < h; i++) tree[i].push_back(i + 1);
  if (d > h) {
    int current = 0;
    int next = h + 1;
    for (int i = 0; i < d - h; i++) {
      tree[current].push_back(next);
      current = next;
      next += 1;
    }
  }
  int current = d + 1;
  for (int i = d + 1; i < n; i++) {
    tree[(d == h) ? 1 : 0].push_back(current);
    current += 1;
  }
  if (get_height() == h)
    for (int i = 0; i < n; i++)
      for (int j = 0; j < (int)tree[i].size(); j++)
        cout << (i + 1) << " " << (tree[i][j] + 1) << endl;
  else
    cout << -1 << endl;
  return 0;
}
