#include <bits/stdc++.h>
using namespace std;
int dir4[4][2] = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
int dir8[8][2] = {{-1, 0}, {1, 0},  {0, 1}, {0, -1},
                  {-1, 1}, {1, -1}, {1, 1}, {-1, -1}};
int dir8h[8][2] = {{2, 1}, {-2, -1}, {-1, 2}, {1, -2},
                   {1, 2}, {-2, 1},  {2, -1}, {-1, -2}};
long double eps = 1e-7;
const int N = 1e5 + 5;
bool vis[N];
int main() {
  ios_base::sync_with_stdio(false);
  int n, d, h;
  cin >> n >> d >> h;
  if (d == h) {
    if (d == 1) {
      if (n == 2)
        cout << 1 << " " << 2;
      else
        cout << -1;
      return 0;
    }
    for (long long i = 1; i <= h - 1; i++) cout << i << " " << i + 1 << "\n";
    for (long long i = h + 1; i <= n; i++) cout << h << " " << i << "\n";
    return 0;
  }
  int h1 = d - h;
  if (h1 > h) return cout << -1, 0;
  int u = 1, v = 2;
  while (h--) cout << u << " " << v << "\n", u = v, vis[v] = 1, v++;
  u = 1;
  while (h1--) cout << u << " " << v << "\n", u = v, vis[v] = 1, v++;
  for (long long i = 2; i <= n; i++)
    if (!vis[i]) cout << 1 << " " << i << "\n";
}
