After you learn enough C to do a small project, I also recommend people get familiar with non-imperative languages. All your languages so far simply tell the computer what to do, not what you want solved.

Learn Prolog, APL, Matlab, and others. Just enough for a small project in each.

Every language you learn will reshape how you think of problem-solving, and the things that are common will be reinforced as well.

You'll boggle as you see Perl features in Ada and Forth and FORTRAN.