I want to upgrade my SHAREPOINT 2013 RTM version to SERVICE PACK1. Also, i have to upgrade my sql server 2012 to SP2 version. so i have completed the sql server upgrade from 2012 to 2012 service pack2. 
MY current Version Number of SP 2013 is 15.0.4420.1017 

Now, how can i upgrade SHAREPOINT 2013 TO SERVICE PACK1 ?
should i upgrade by directly running the sharepoint 2013 SP1 ISO FILE? 
or 
should i just run the SP1 EXE thats freely available from msft download center?
i have attached my current SP 2013 version number:
 [![SP2013-VERSION-NUM](https://i.stack.imgur.com/TDcob.png)](https://i.stack.imgur.com/TDcob.png)