#include <bits/stdc++.h>
using namespace std;
vector<long long> v[100001];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long N, d, h, T, i, j, k;
  cin >> N >> d >> h;
  if (d < h || d > 2 * h) {
    cout << "-1" << endl;
    return 0;
  }
  if (h > N - 1 || d > N - 1) {
    cout << "-1" << endl;
    return 0;
  }
  if (d == 1 && h == 1) {
    if (N != 2)
      cout << "-1" << endl;
    else
      cout << "1 2\n";
    return 0;
  }
  for (i = 0; i < h; i++) {
    v[i].push_back(i + 1);
  }
  j = h + 1;
  long long rem = d - h;
  if (d - h > 0) {
    v[0].push_back(j);
    rem--;
    for (i = j; i < N - 1 && rem > 0; i++) {
      v[i].push_back(i + 1);
      rem--;
    }
    long long r = i + 1;
    for (i = r; i < N; i++) {
      if (h > 1)
        v[1].push_back(i);
      else
        v[0].push_back(i);
    }
  } else {
    for (i = j; i < N; i++) v[1].push_back(i);
  }
  for (i = 0; i < N; i++) {
    for (j = 0; j < v[i].size(); j++) {
      cout << i + 1 << " " << v[i][j] + 1 << endl;
    }
  }
}
