I'm a beginner in UNIX. So I can do this in 6 steps.

1) ls -l | awk '{print $9}' > getfilenames1.txt
2) cp filenames1.txt filenames2.txt
3) vi filenames2.txt
i) :%s/ff.//g
4) vi filenames1.txt
i) :%s/^/mv /g # note blant after mv
5) paste -d" " filenames1.txt filenames2.txt > filename3
6) run filename3.

I know it can be done in one command at the prompt. But as a beginner, I have to try.