Write a automation script in PERL compare.pl

where::

1. there are two folders. Folder X has a file named file1.txt. In this file, There is a value (say, aaa sqcm). Another folder Y has a file named file2.txt. In File2.txt has a value (say, yyy sqcm).
2. then substract these two values.
3. if difference is 0 then No error and if difference is not 0, then error

Show in your PERL Script