#include <bits/stdc++.h>
using namespace std;
int dia[1123456];
int main() {
  int n, d, h;
  scanf("%d%d%d", &n, &d, &h);
  if (n > 2 && d == 1 && h == 1) {
    printf("-1\n");
    return 0;
  }
  if (2 * h < d) {
    printf("-1\n");
    return 0;
  }
  for (int i = 1; i <= d + 1; ++i) dia[i] = i;
  swap(dia[1], dia[h + 1]);
  for (int i = 1; i <= d; ++i) printf("%d %d\n", dia[i], dia[i + 1]);
  for (int i = d + 2; i <= n; ++i) printf("%d %d\n", i, dia[2]);
  return 0;
}
