Mathematics, because it requires a high degree of concentration, dedication, analysis: Sets, derived from a function, integration, integration methods, geometry of space and vectors, multiple integrals, series and sequences, differential equations, etc, constitute a vast universe where you can deepen anything you want. Study mathematics occupy all your time for several years. There is no place to superficiality. If you make a wrong analysis, bad results, and will fail in your job whatever.

I prefer mathematics, it doesn't have a long explanation about thing because it is just a number.

My favorite is history because to fully understand the present day world you must also understand its history.

How to make homemade ice cream.

Communication & Media Studies