#include <bits/stdc++.h>
using namespace std;
int main(int argc, const char **argv) {
  if (argc == 2) {
    freopen(argv[1], "r", stdin);
  }
  int n, d, h;
  cin >> n >> d >> h;
  if (d > 2 * h) {
    cout << -1 << endl;
    return 0;
  }
  if (d == 1 && h == 1 && n > 2) {
    cout << -1 << endl;
    return 0;
  }
  int r1 = d - h;
  int r2 = h;
  int p = 1;
  int k = 2;
  for (int i = 0; i < r1; i++) {
    printf("%d %d\n", p, k);
    p = k++;
  }
  p = 1;
  for (int i = 0; i < r2; i++) {
    printf("%d %d\n", p, k);
    p = k++;
  }
  if (d == h) {
    while (k <= n) {
      printf("2 %d\n", k++);
    }
  } else
    while (k <= n) {
      printf("1 %d\n", k++);
    }
}
