I've never had any need for Latin. I suggest learning a language that would come in useful. I took Russian - that's never come in useful. Now I need to learn German and Spanish. German because my collaborators are in Germany and I often travel there, and Spanish because all our telescopes are in Chile and I spend a lot of time down there as well.
I know that most graduate schools in math that require a foreign language accept French as one of the choices. The three choices are usually German, Russian and French. That said, I don't know what the chances are that you will actually use French at all beyond that.