#include <bits/stdc++.h>
using namespace std;
void dfs(int s) {}
int main() {
  long long n, d, h, cnt = 0;
  cin >> n >> d >> h;
  if (h * 2 < d || (d == 1 && h == 1 && n > 2)) {
    cout << -1 << endl;
  } else {
    for (int i = 1; i <= h; i++) {
      cout << i << " " << i + 1 << "\n";
    }
    int t = 1;
    for (int i = h + 2; i <= d + 1; i++) {
      cout << t << " " << i << "\n";
      t = i;
    }
    for (int i = d + 2; i <= n; i++) {
      cout << h << " " << i << "\n";
    }
  }
  return 0;
}
