How to find lines in a file that are missing in another file?

Question

excel

Good afternoon. Please tell me how can I find out the number of unique lines in the A.txt file that are missing in the B.txt file? Each line is a set of ID numbers. Files up to 15mb.

Answer 1

Upload files to excel (in sheets or books) and make VLOOKUP(ID; table; 1; 0), filter by #N/A and make advanced filter unique records

Answer 2

Excel hangs from such volumes. 680000 cells. I figured out how to do it differently through Notepad ++, a little crooked, but in principle, he gives the data that I need.

Answer 3

macros, of course.