fuck btech i will do bs maths, need help on choosing

i mean it, throughout these 2 years i never had a single hunch for cs or high paying tech jobs. always have been interested in maths( not a genius just more curious) if only i had some good counselling at 10th i wouldnt have entered the jee facade anyway, now i have realised if i dont stand up for what i want i will be stuck somewhere i dont want to be the rest of my life. i saw that through jeeM you can get only 2 courses on bs maths ( at nit agartala and nit rourkela) and thorugh Jee A its impossible due to dweebs taking the seats so they can sit for placements rather then study maths. my dad is supportive (big physics nerd did bs and ms)i havent told him this yet. i fked up my jee mains with 15 negative, i will most probably bring a better score at april attempt can you tell me how much rank would one need to get in bs maths at nit rourkela? closing round numbers would help too. online their is a 30000 rank delta in opening and closing. please advise