#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h;
  cin >> n >> d >> h;
  if (n > h) {
    if (d > 2 * h || d < h) {
      cout << "-1\n";
      return 0;
    } else if (d == h) {
      if (n == h + 1) {
        for (int i = 1; i < n; i++) cout << i << " " << i + 1 << "\n";
        return 0;
      } else if (n > h + 1 && h != 1) {
        for (int i = 1; i <= h; i++) cout << i << " " << i + 1 << "\n";
        for (int i = h + 2; i <= n; i++) cout << 2 << " " << i << "\n";
      } else {
        cout << "-1\n";
        return 0;
      }
    } else if (n > d) {
      for (int i = 1; i <= h; i++) cout << i << " " << i + 1 << "\n";
      int var = h + 1, var1 = 0;
      int x = d - h;
      int i;
      for (i = 1; i <= x; i++)
        cout << var1 + i << " " << var + i << "\n", var1 = var - 1;
      int var3 = var + i;
      for (int i = var3; i <= n; i++) cout << 1 << " " << i << "\n";
    } else
      cout << "-1\n";
  } else
    cout << "-1\n";
}
