Cst related query

Dear Sir, I have started a New Business in west bengal for 2 month.my business is Vat registor dealer but not CST registor dealer till date.So I have purchased some product from outside west bengal.But these product are being sold in local market.but when i am purchasing in CST @ 2%.and i am selling in Vat @ 5%...in this case i take CST @ 2% as indirect expenses? Suppose..ItemA cost at RS.100(Indluding Excise duty)+ 2(CST @ 2% on Rs.100).Total Cost Price Rs.102. Sir Please Give me answer as soon as possible.