The service has some restrictions on input size, memory and execution time. They should be more than fair for what you need, but if for some reason you think they are too restrictive, let me know and we'll have a look.
For those who are wondering what QD means, perhaps you should move your nose off the screen. :p It's right there, ffs! Some people make challenges out of anything and nothing... ;)
The only thing I'm not sure about is how hard it is to understand what is going on exactly. You should be able to deduce a few things, but perhaps it is not enough to power your light bulb. When you have deduced a fair number of things and can't make any more sense of it, feel free to contact me. If needed, I'll extend the cheat sheet a bit.