Shell Programming and Scripting

Hello
can someone please help me with this task:
I am in the shell, in folder "Main"
below the folder Main are sub folders: "sourceA", "Source B", and "target"

in sourceA and source B are files, and in folder "Main" is a textfile, with filenames, one filename per line.

I need a shellscript that:
1. reads the textfile line per line...
2. finds the file either in sourceA or sourceB and copies it to "target"
3. or, if the searched file is in neither folder, writes an error like "File XY not found" into a new textfile

Thank you very much in advance for looking into this

Looks very much like homework!
What have you done so far?

maybe smthg like :

Code:

( find ./@(sourceA|sourceB) -type f -prune) | grep -f textfile | while read a
do
cp $a target/${a##*/}
done

Sorry, i was not participating in any classes or homework or the like here i really am mainly a ubuntu desktop user, i am not earning my money with unix or linux shell scripting, but need all in all three tips so far to get a one time problem i have there, done.

So, as i said, any help is appreciated

thank you ctsngb, this worked perfectly well and helped me saving time a lot.