puts\
"Problem for testing of new exec filter (it's faster the previous one). Volunteers are needed: please submit code in your favorite language and report me if you find:
- valid code is rejected.
- code which uses exec is accepted.
This problem will be removed after a while."\
.gsub(/[^pong]/m,'').split('').sort.uniq.reverse.join
Note that non-ascii characters in the above source code will be escaped (such as \x9f).