UVa 10696 - f91

10696 - f91

 * http://acm.uva.es/p/v106/10696.html

Summary
This problem is funny. There are no tricks, and there are quite a few ways to "solve" this, and it's easy to code.

Explanation
No explanations needed, simply follow the calculation, doing it recursively, figuring out a pattern, it doesn't get much easier than this!

Gotcha's

 * 0 is not part of the test set.

Input
500 91 0

Output
f91(500) = 490 f91(91) = 91