#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, h, d;
  cin >> n >> d >> h;
  if (d > h * 2 || (d < 1 + (n > 2)))
    cout << -1;
  else {
    int k = d % h;
    int x = 1, y = 2;
    int t = n - 1, r = 0;
    while (k-- && t > 0) {
      cout << x << ' ' << y << endl;
      x = y;
      y++;
      t--;
    }
    x = 1;
    if (d == h * 2)
      while (t > 0) {
        cout << x << ' ' << y << endl;
        x = y;
        y++;
        r++;
        t--;
        if (r == h) {
          x = 1;
          r = 0;
        }
      }
    else {
      while (t > 0) {
        cout << x << ' ' << y << endl;
        x = y;
        y++;
        r++;
        t--;
        if (r == h) break;
      }
      x--;
      while (t--) cout << x << ' ' << y++ << '\n';
    }
  }
  return 0;
}
