Custom workflow how to get the execution entity

This is my first custom WF for CRM 2011, and this needed to be a generic EF for any entity, I would like to know how to get the execution entity from the context or if not possible, any idea would be very nice.

I start the WF like this:

public class WFIntegracao: CodeActivity
    {

        protected override void Execute(CodeActivityContext context)
        {

            IWorkflowContext contexto = context.GetExtension<IWorkflowContext>();


        }
    }