#include <bits/stdc++.h>
using namespace std;
int n, d, h, i;
int ans[100010][3] = {};
int num;
bool bj = 0;
int main() {
  cin >> n >> d >> h;
  if (d == 1)
    puts(n == 2 && h == 1 ? "1 2" : "-1");
  else if (d > 2 * h)
    puts("-1");
  else {
    num = 0;
    for (i = 2; i <= h + 1; i++) {
      num++;
      ans[num][1] = i - 1;
      ans[num][2] = i;
    }
    if (h + 2 <= n && d > h) {
      num++;
      ans[num][1] = 1;
      ans[num][2] = h + 2;
    }
    for (i = h + 3; i <= d + 1; i++) {
      num++;
      ans[num][1] = i - 1;
      ans[num][2] = i;
    }
    for (i = d + 2; i <= n; i++) {
      num++;
      ans[num][1] = h;
      ans[num][2] = i;
    }
    for (i = 1; i <= n - 1; i++) {
      cout << ans[i][1] << " " << ans[i][2] << endl;
    }
  }
  return 0;
}
