migration crm 4.0 to crm 2015

Hi

Do i necessary need to deploy the restoration backup from crm 4.0 to crm 2011 and making the same on crm 2013 from crm 2011 before crm 2015 or i can just take the backup of database of crm 4.0 and restore it on crm 2015 directly,and just make the correction, validation code and other transformation because the sdk  isn't the same?

Thanks by advance

Regards