I think it is very important to get exposed to several different computer languages, fairly early in the game. And I don't mean different like C and C++ and C#. I mean really different, languages that drive in the richness of ways you can express algorithms.
Few things are as tedious as the language snob who thinks that whatever language his comp sci course used is best, or the one that has the largest number of job openings is best.
I don't know what would be a good set to suggest, and I am most familiar with antiques; but if we assume that one of them is going to have C-like syntax, then I would suggest, as mind-stretchers: assembly language--of course; some language in which "loops" are not central to the language, examples being APL or FORTH or PostScript; some language in which symbols rather than numbers are paramount, such as LISP or SNOBOL; some language in which indentation is significant, such as MUMPS or Python.