Keep Remote Up-to-date - Whitelist directory

I have directories

d:\www\a
d:\www\b
d:\www\c
...
d:\www\z

I want to sync directories a and b to the remote server.

How do I set the mask to include all files recursively ONLY in directories a and b? I tried the following but it didn't work:

/www/a/; /www/b/


Thanks.

This should do: */a/*; */b/*

See https://winscp.net/eng/docs/file_mask#path