Hi Santosh,
I think you are looking for time off compensation scenario. You know you can give extra pay for extra work which we call overtime, or extra leave(paid absence) allowance for extra work, or a combination of these.
Your requirement is not so clear for me. What you would do with "Snacks Allowance"? You would pay in payroll or generate quota in PT side?
Would you just count the days EE had extra work? It's not important s/he how many extra hours has been worked?
Regards,
Omid