Ditto anyone who said ocaml or haskell. :-)

But, seriously, if you don't already know C, I'd learn that first. It is extremely useful to have a good understanding of how real (vs. virtual) machines work, to get close to the metal, as they say. C will give you that.

Then I'd learn Java.

Sure, both those languages have syntax similar to each other and Perl... but syntax is the least of your worries. The conceptual model behind each of them is significantly different, yet not so exotic as to be very difficult to comprehend.