Hi mohan,

Based on category and resevations u may get seat in that college i mean to say iiit allahabad but u may or may not get cse branch in that college as its a top college so that chances are less compared to previous years cutoff marks and estimations as your having a reservation of  OBC so that u have some plus point to get chances are there but i cannot give u that complete  chances are there u may or may not get and to calculate the ranks and we can predict  ranks by using formula below

Percentile calculation- {(Maximum rank – Rank of the Candidate)* 100} / Maximum Rank.

Based on resevations and percentile u will get your rank.

So work hard for the coming exams and study well and score good marks in the exams  All the best  for your future i think my suggestions and knowledge may be helpful to u.