You receive a credit card application from Shady Banks Savings and Loan offering an introductory rate of $3\mathrm{.}7$ percent per year, compounded monthly for the first six months, increasing thereafter to $18\mathrm{.}6$ percent per year, compounded monthly. Assuming you transfer the $$18,000$ balance from your existing credif card and make no subsequent payments, how much interest will you owe at the end of the first year?

Note: Do not round intermediate calculations and round your answer to $2$ decimal places, e$.$g$.,32\mathrm{.}16.$