public void OnRequestFinishedButtonClicked()
    {
        // give items to NPC
        foreach (string id in questGoal.Keys)
        {
            bm.LoseItem(id, questGoal[id]);
            Debug.Log("Finish quest, you lost " + id + questGoal[id]);
        }
        requestFinishButton.gameObject.SetActive(false);

        // give reward to player
        foreach (string id in rewards)
        {
            bm.AddItem(id);
            Debug.Log("You get the reward" + id);
        }
    }