Thanks for this easy question. But it remembers me an interview in 2010 where I have not been able to give the good solution ( the sysadmin permission was too much trivial to be accepted by the interviewer ). But the interviewer was clever and used the computer on his table to show me the results : a simple way which avoids many discussions and pleasant as it is easier for me to remember something I have seen/read than listened. But an habit too much forgotten or ignored by interviewers ...