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