You notice what it did, it printed out that little, right up here I'd said enter a number and that's what it's printed out, so I can enter a number and it prints it out.

注意这个程序做了些什么，显示出了指定值，然后显示需要输入个数字,然后程序会显示这个数字，我输入一个数字然后程序显示了它。

麻省理工公开课 - 计算机科学及编程导论课程节选