世界是个好地方,值得为之奋斗。
有一个人从天堂来到人间旅游,他所使用的是有效三十天的减价票,他试图要把他的回程票卖掉。
小于给定数的素数个数是该数的一个函数。
"I think the most important thing is to enjoy what you're doing. If you enjoy it, then you'll do it well."