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