#include <bits/stdc++.h>
using namespace std;
const int N = 100010;
int main() {
  int n, h, d;
  cin >> n >> d >> h;
  int cur = (d + 1) / 2;
  if (cur > h) {
    puts("-1");
    return 0;
  }
  if (n > 2 && d == 1) {
    puts("-1");
    return 0;
  }
  for (int i = 0; i < h; i++) {
    printf("%d %d\n", i + 1, i + 2);
  }
  int pre = 1;
  for (int i = h + 2; i <= d + 1; i++) {
    printf("%d %d\n", pre, i);
    pre = i;
  }
  for (int i = d + 2; i <= n; i++) {
    if (h != d)
      printf("1 %d\n", i);
    else
      printf("2 %d\n", i);
  }
  return 0;
}
