#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h, i = 1;
  cin >> n >> d >> h;
  if (d > h * 2 || (n > 2 && d < 2)) {
    cout << -1 << endl;
  } else {
    while (i <= h) cout << i++ << ' ' << i << endl;
    if (i <= d) cout << 1 << ' ' << ++i << endl;
    while (i <= d) cout << i++ << ' ' << i << endl;
    int r = 1 + (d == h && h > 1);
    while (i < n) cout << r << ' ' << ++i << endl;
  }
  return 0;
}
