Hello

I've got an unusual question, or at least I think it is.  I'm trying to teach myself C/C++.  So far, I can understand the basics of what I'm reading (Teach yourself C for linux programming in 21 days/Teach yourself C++ for linux in 21 days).   This isn't the first time I've started either of these books and not been able to finish them for one reason or another.  The biggest problem I'm coming up against is finding problems that are incrementally hard enough to continue my interest in learning the languages.   My question is this: Does anyone know of either problems or websites that have problems posted that get incrementally harder, thereby forcing the person trying to learn the subject, without being too easy or too hard.  I'm looking for something/someplace that posts a problem that can get solved in an approximate amount of lines.  As an example, maybe a problem that's used to figure something out, and can usually be coded in under 100 lines, 500 lines, 1000 lines, more, etc.  I just need incrementally harder problems to work with so I can get better.  All the ideas for programs that I come up with, I can't figure out where to start due to their initial complexity, like stock forecasting , weather tracking, video game, etc.  Any help, sample problems, or references would be appreciated.  Thanks in advance.