Dear I done M.Sc in Pure Math.
As according to new syllabus Pure and Applied Math are in one section.
You will choose both or if you choose one then remaining option is Statistics.
Math paper would be Zero or Hero.
Second CSS is not an exam of Knowledge and analysis it is also exam of muscles and strangeness of the body.
Math need more time , it is a practical subjects . But in CSS two paper per day are very tough and tiring time.
It is better to choose those subjects you can revise easily.
In case of math a much time needed and if you have firm grip go through the Math , Insha Allah you will score well.
Another suggestion is , you should read the CE 2016 past papers of mathematics , you can easily judge yourself.

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