lesson of the day.....

#1: if you are not working here, you can just see other people buying stuff and use it.
in other word, get a job now!.

#2: mathematics needs practice. how easy it is, without practice, you can't do it.
in other word, don't skip calculus class again!.

#3:don't procrastinate. or you end up at 5 am in front of the computer.
in other word, sleep now!!!