#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
vector<long long> v[N];
void solve() {
  long long n, d, h;
  cin >> n >> d >> h;
  if (d > 2 * h) {
    cout << "-1\n";
    return;
  }
  if (d < h) {
    cout << "-1\n";
    return;
  }
  if (n < h + 1) {
    cout << "-1\n";
    return;
  }
  if (n < d + 1) {
    cout << "-1\n";
    return;
  }
  if (d == 1) {
    if (n > 2) {
      cout << "-1\n";
      return;
    }
  }
  long long cur = 0;
  long long no = 1;
  long long xx = d - h;
  long long hh = h;
  while (hh > 0) {
    v[cur].push_back(no);
    cur = no;
    no++;
    hh--;
  }
  cur = 0;
  if (xx == 0) {
    cur = v[0][0];
    while (no < n) {
      v[cur].push_back(no);
      no++;
    }
  } else {
    while (xx > 0) {
      xx--;
      v[cur].push_back(no);
      cur = no;
      no++;
    }
    cur = 0;
    while (no < n) {
      v[cur].push_back(no);
      no++;
    }
  }
  long long i, j;
  for (i = 0; i < n; i++) {
    if (v[i].size() == 0) continue;
    for (auto it : v[i]) {
      cout << i + 1 << " " << it + 1 << "\n";
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  if (fopen("input.txt", "r")) {
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
  }
  cout << setprecision(20);
  long long t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
