There are regular after-contest competitions on Topcoder named shortest code competitions. Sometimes it is very interesting to see how the code of some easy task can be compressed to weird and unreadable one, but at the same time this code passes all the test cases. I suggest to hold such competitions here.
I will start from task C from Codeforces Beta Round #24. The rules are simple: each next code should be shorter than previous one. The winner is the person whose code is not beaten by anyone else. Length of the code is the number of non-whitespace characthers in it. Of course, the code should be AC on at least one of the allowed compilers. As far as I know, defines are not used on Topcoder shortest code competitions, so I suggest not to use them here either.
There are some special features in different languages, so I suggest to have different standings for different languages, because I doubt that C++ or Pascal can compete with Haskell or Python.
__int64 n,k,x,y,a[' '],b[' '],d;
for (d=0,k-=n;k>0;--k,++d) x=2*a[d]-x,y=2*b[d]-y;