#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h, i, j;
  cin >> n >> d >> h;
  vector<vector<int> > g(n);
  if ((d > 2 * h) || (d < h) || ((d == 1) && (n > 2)) || (d > n - 1)) {
    cout << -1 << endl;
    return 0;
  } else if (n == 2) {
    if ((d != 1) || (h != 1)) {
      cout << -1 << endl;
      return 0;
    }
  }
  int num = 1;
  for (i = 0; i < h; i++) {
    g[i].push_back(num);
    num++;
  }
  int k = d - h;
  int cur = 0;
  for (i = 0; i < k; i++) {
    g[cur].push_back(num);
    cur = num;
    num++;
  }
  for (i = 0; i < n - num; i++) {
    g[h - 1].push_back(num + i);
  }
  for (i = 0; i < n; i++)
    for (j = 0; j < g[i].size(); j++)
      cout << i + 1 << ' ' << g[i][j] + 1 << endl;
  return 0;
}
