sclass AscendingOrderIntObjectMap<A> {
  new IntBuffer keys;
  new L<A> values;
  
  void put(int key, A value) {
    if (!keys.isEmpty() && last(keys) >= key)
      fail("Ascending order fail: " + last(keys) + " / " + key);
    keys.add(key);
    values.add(value);
  }
  
  A get(int key) {
    int i = intBufferBinarySearch(keys, key);
    ret i >= 0 ? values.get(i) : null;
  }
  
  int size() { ret keys.size(); }
}