#include <bits/stdc++.h>
using namespace std;
int n, d, h, curr, nxt, corner1, corner2, chosen;
queue<pair<int, int> > q;
int main() {
  scanf("%d%d%d", &n, &d, &h);
  if (d > 2 * h) {
    printf("-1\n");
    return 0;
  }
  curr = 1;
  nxt = 2;
  for (int i = 0; i < h; i++) {
    q.push(make_pair(curr, nxt));
    curr = nxt;
    nxt = curr + 1;
  }
  corner1 = curr;
  curr = 1;
  for (int i = 0; i < d - h; i++) {
    q.push(make_pair(curr, nxt));
    curr = nxt;
    nxt = curr + 1;
  }
  corner2 = curr;
  for (int i = 1; i < max(corner1, corner2); i++) {
    if (i != corner1 && i != corner2) {
      chosen = i;
      break;
    }
  }
  if (chosen == 0 && nxt <= n) {
    printf("-1\n");
    return 0;
  }
  while (nxt <= n) {
    printf("%d %d\n", chosen, nxt);
    nxt++;
  }
  while (!q.empty()) {
    printf("%d %d\n", q.front().first, q.front().second);
    q.pop();
  }
}
