Sir, I believe I can do this task easily. It is a simple programming routine. I will store the entries of both the files in a set and send the intersection in the result file all of which can be done in nlgn time which means if there are 1,000,000,000 entries in both files each, my algorithm will take less than 30 seconds to generate the result file. I will need to take a look at both the files in a greater detail to speak with more certainty.