#include <bits/stdc++.h>
using namespace std;
long long factorial(long long n) {
  return (n == 1 || n == 0) ? 1 : n * factorial(n - 1);
}
long long gcd(long long a, long long b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
long long lcm(long long a, long long b) { return (a * b) / gcd(a, b); }
bool sortByVal(const pair<long long, long long> &a,
               const pair<long long, long long> &b) {
  if (a.first == b.first)
    return a.second < b.second;
  else
    return a.first > b.first;
}
long long Powb(long long b, long long n) {
  if (n == 0) return 1LL;
  if (n == 1) return b;
  long long temp = Powb(b, n / 2);
  if (n % 2 == 0) {
    return (temp * temp) % 1000000007LL;
  } else {
    return (b * ((temp * temp) % 1000000007LL)) % 1000000007LL;
  }
}
long long root(vector<long long> &a, long long i) {
  while (a[i] != i) {
    a[i] = a[a[i]];
    i = a[i];
  }
  return i;
}
void wunion(vector<long long> &a, vector<long long> &size, long long i,
            long long j) {
  long long root_i = root(a, i);
  long long root_j = root(a, j);
  if (root_i == root_j) return;
  if (size[root_i] < size[root_j]) {
    a[root_i] = a[root_j];
    size[root_j] += size[root_i];
    size[root_i] = 0;
  } else {
    a[root_j] = a[root_i];
    size[root_i] += size[root_j];
    size[root_j] = 0;
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  int t = 1;
  while (t--) {
    long long i, j, m, n, k, sum = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0,
                             maxi = 0;
    cin >> n >> d >> k;
    if (d == 1 && k == 1 && n != 2)
      cout << -1 << "\n";
    else if (d > 2 * k)
      cout << -1 << "\n";
    else {
      f = k;
      for (i = 2; i < k + 2; i++) cout << i - 1 << " " << i << "\n";
      c = d - k;
      k += 2;
      e = 1;
      for (i = 0; i < c; i++) {
        cout << e << " " << k << "\n";
        k++;
        e = k - 1;
      }
      if (d == f) {
        for (i = k; i <= n; i++) cout << 2 << " " << i << "\n";
      } else {
        for (i = k; i <= n; i++) cout << 1 << " " << i << "\n";
      }
    }
  }
}
