#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
const int N = 1e5 + 20;
const double eps = 1e-8;
int main() {
  int n, w, h;
  while (cin >> n >> w >> h) {
    if (h * 2 < w || n - 1 < h || n - 1 < w || (w == 1 && n > 2)) {
      printf("-1\n");
      continue;
    } else if (n == 2) {
      printf("1 2\n");
      continue;
    }
    int cnt = 2;
    for (int i = 0; i < w - h; i++) {
      printf("%d %d\n", cnt - 1, cnt);
      cnt++;
    }
    int p = 1;
    for (int i = 0; i < h; i++) {
      printf("%d %d\n", p, cnt);
      p = cnt;
      cnt++;
    }
    if (true) {
      if (w != h)
        p = 1;
      else
        p = cnt - 2;
      for (int i = cnt; i <= n; i++) {
        printf("%d %d\n", p, cnt);
        cnt++;
      }
    }
  }
  return 0;
}
