安装的MySQL的版本为5.7,其他版本可能不适用
下载的链接为https://dev.mysql.com/get/Downloads/MySQL-5.7/mysql-5.7.19-winx64.zip
如果想下载其他版本的MySQL:https://downloads.mysql.com/archives/community/
我推荐使用.zip文件进行安装，如果使用installer进行安装会修改注册表，导致以后彻底删除MySQL很麻烦。

question

We have a two dimensional matrix A where each value is 0 or 1.

A move consists of choosing any row or column, and toggling each value in that row or column: changing all 0s to 1s, and all 1s to 0s.

After making any number of moves, every row of this matrix is interpreted as a binary number, and the score of the matrix is the sum of these numbers.

Return the highest possible score.

question

Implement pow(x,n), which calculates x raised to the power n (i.e. xn).

question

Count the number of prime numbers less than a non-negative number, n.