#include <bits/stdc++.h>
using namespace std;
long long n, d, h;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> d >> h;
  if (d > 2 * h || (h == d && d == 1 && n > 2)) {
    cout << -1 << endl;
  } else {
    for (long long i = 1; i <= h; i++) cout << i << " " << i + 1 << endl;
    long long j = 1;
    for (long long i = h + 2; i <= d + 1; i++) {
      cout << j << " " << i << endl;
      j = i;
    }
    for (long long i = d + 2; i <= n; i++) cout << h << " " << i << endl;
  }
}
