#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:102400000,102400000")
template <class T>
inline void gmax(T &a, T b) {
  if (b > a) a = b;
}
template <class T>
inline void gmin(T &a, T b) {
  if (b < a) a = b;
}
using namespace std;
const int N = 1e5 + 10, M = 2e6 + 10, Z = 1e9 + 7, maxint = 2147483647,
          ms1 = 16843009, ms31 = 522133279, ms63 = 1061109567,
          ms127 = 2139062143;
const double PI = acos(-1.0), eps = 1e-8;
void fre() {
  freopen("/Users/luras/Desktop/in.txt", "r", stdin);
  freopen("/Users/luras/Desktop/out.txt", "w", stdout);
}
const int INF = 1e9;
int casenum, casei;
int n, d, h, x;
int main() {
  while (~scanf("%d%d%d", &n, &d, &h)) {
    if (d > min(n - 1, 2 * h) || d < h) {
      puts("-1");
      continue;
    }
    if (h == 1 && d == 1 && n != 2) {
      puts("-1");
      continue;
    }
    x = d - h;
    for (int i = 1; i <= x; i++) {
      printf("%d %d\n", i, i + 1);
    }
    x += 2;
    printf("%d %d\n", 1, x);
    for (int i = 1; i < h; i++) {
      printf("%d %d\n", x, x + 1);
      x++;
    }
    if (h == 1) {
      x--;
      for (int i = x + 2; i <= n; i++) {
        printf("%d %d\n", 1, i);
      }
    } else {
      x--;
      for (int i = x + 2; i <= n; i++) {
        printf("%d %d\n", x, i);
      }
    }
  }
  return 0;
}
