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