Minimum size of employees for registration of esi and epf in andhra pradesh

We want to registration of employees ESI and EPF under the shops and establishment act. Our size of employees are just 5 nos and one of them draws morethan 15000/-. Can we approach to registration of ESI and EPF ? Is it possible or not and one thing, we paid the salaries to the employees through cash and also we have a sister concern, their employees are 4 nos. Can anyone give valuable suggestion about my query.