Let $f$ be the function such that $f(x,y,z,w)=x+w, \quad x,y,z,w\in{\Bbb Z}$ where $ x+y+z+w=400, $ and $x
I think the key point is to use $x
[EDITED:] According to answers, $\max f=+\infty$. What's the minimum of $f$? I think there should be a bound. Playing around the examples, I think $\min f$ should be given by $(98,99,101,102)$. Any examples "better" than this?