#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, h, d;
  int c1, c2;
  cin >> n >> d >> h;
  if (h <= 0 || h > n - 1 || d > 2 * h || d < h || (h == n - 1 && d != n - 1)) {
    cout << -1 << endl;
    return 0;
  }
  if (h != d || n == 2) {
    c1 = h;
    c2 = d - h;
    for (int i = 0; i < c1; i++) {
      cout << i + 1 << " " << i + 2 << endl;
    }
    int prev = 1;
    for (int i = 0; i < c2; i++) {
      cout << prev << " " << i + c1 + 2 << endl;
      prev = i + c1 + 2;
    }
    for (int i = c1 + c2 + 2; i <= n; i++) cout << 1 << " " << i << endl;
  } else if (h < 2 && d == h) {
    cout << -1 << endl;
  } else {
    c1 = h;
    c2 = d - h;
    for (int i = 0; i < c1; i++) {
      cout << i + 1 << " " << i + 2 << endl;
    }
    for (int i = c1 + c2 + 2; i <= n; i++) cout << 2 << " " << i << endl;
  }
}
