message: Corrected order to ascending
  Corrected findKthInSortedArrays to work with k starting from start, not from end.
  Old version passed all tests also, but now users can reuse this function to really get Kth element in the merged array.
diff: @@ -84,10 +84,10 @@ private:
  int res = 0;
  for (const auto array : arrays) {
  if (!array->empty()) {
  - res += distance(upper_bound(array->cbegin(), array->cend(), num),
  - array->cend());
  + res += distance(array->cbegin(),
  + upper_bound(array->cbegin(), array->cend(), num));
  }
  }
  - return res < target;
  + return res >= target;
  }
  };
  