For challenge problem setters!

In general I put 1-2 problems on each week from challenge section to tutorial, because of the poor quality/triviality of the problem.
What I would not like to see: add two integers, multiple two integers. And these trivial combination's. Examples for this (moved these from challenge to tutorial today):

http://www.spoj.com/problems/SUMOF/64: "sum of the numbers from A to B."
http://www.spoj.com/problems/FACKT/28: "Write a program that calculates factorial of namber N; Integer N(0<16)."

For interesting problems see the first 50 challenge problems, to get an impression what is quality.