Assume the spot Swiss franc is $$0\mathrm{.}7056$ and the six$-$month forward rate is $$0\mathrm{.}6978.$ What is the minimum price that a six$-$month American call option with a striking price of $$0\mathrm{.}6828$ should sell for in a rational market? Assume the annualized six$-$month Eurodollar rate is $3\mathrm{.}5$ percent. $($Do not round intermediate calculations. Round your answer to $2$ decimal places.$)$