i think c is a really nice programming language, it's compact and somewhat easy to learn.
but if you only want to learn c++ start with c++. but i suggest you to learn both. and if you want to do that; i think it's better to start with c. as said before: it's small and somewhat easy to learn. might be a nice step-up to a more complex programming language as c++. (since c provides you with some basics)
good luck.