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