solved maven problem in Windows

I struggled a lot to install maven in windows 7 in my acer laptop. I could not execute mvn -version in CMD. I used to get the below error in CMD.

"org.codehaus.plexus.classworlds.launcher.ConfigurationException: Unhandled configuration (4)"

There was problem putting environment variables in system properties (Win+Pause/Break).

Initially I created two system variables i.e. MAVEN_HOME and M2_HOME. That was a mistake I guess. Then I deleted MAVEN_HOME and kept only M2_HOME. I updated M2_HOME in path variable as %M2_HOME% now it worked.

I executed C:\mvn -version it worked. 

C:\>mvn -version
C:\
Apache Maven 3.3.9 (bb52d8502b132ec0a5a3f4c09453c07478323dc5; 2015-11-10T22:11:4
7+05:30)
Maven home: C:\maven
Java version: 1.7.0_79, vendor: Oracle Corporation
Java home: C:\Java\jdk1.7.0_79\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 7", version: "6.1", arch: "x86", family: "windows"


C:\>

Now I got to see if I can build Hadoop with the help of maven!