#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h;
  scanf("%d %d %d", &n, &d, &h);
  if (h == 1 && d == 1 && n > 2) {
    printf("-1\n");
    return 0;
  }
  if (h > d || (n - 1) < d || (n - 1) < h || 2 * h < d)
    printf("-1\n");
  else {
    for (int x = 2; x <= h + 1; x++) {
      printf("%d %d\n", x - 1, x);
    }
    int ult = 1;
    for (int x = h + 2; x <= d + 1; x++) {
      printf("%d %d\n", ult, x);
      ult = x;
    }
    if (d > h) {
      for (int x = d + 2; x <= n; x++) {
        printf("%d %d\n", 1, x);
      }
    } else {
      for (int x = d + 2; x <= n; x++) {
        printf("%d %d\n", 2, x);
      }
    }
  }
  return 0;
}
