[OciXCrom]

If you want only one reward, you can use multiple flags and separate the users or not use multiple rewards at all. In most cases there will be multiple rewards on multiple flags, so people would want to combine them. For example, you buy the "b" flag which gives you 1000$, then you buy the "c" flag which gives you 500$, so you will probably want to get 1500$ instead of 1000$.