Download sharepoint 2013 service pack 1 results in 3 files, which file is correct

Download sharepoint 2013 service pack 1 results in 3 files:

officeserversp2013-kb2880552-fullfile-x64-en-us.exe

projectserversp2013-kb2880553-fullfile-x64-en-us.exe

sharepointsp2013-kb2880551-fullfile-x64-en-us.exe

In intallation instructions only the file officeserversp2013-kb2880552-fullfile-x64-en-us.exe is executed. Do I need the other two files? Are they part of the installation or is it something else?