Uh oh! Wolfram|Alpha doesn't run without JavaScript.
Please enable JavaScript. If you don't know how, you can find instructions
here
.
Once you've done that, refresh this page to start using Wolfram|Alpha.
welcome注册登录（永久链接:SE8.TV）welcome注册登录_welcome注册登录_welcome注册登录_a22aKKgu2
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random
