Your firm is considering issuing one$-$year debt and has come up with the following estimates of the value of the interest tax shield and the probability of distress for different levels of debt:

Debt Level $($in $ million$)$

$01030507090110$

PV $($interest tax shield, in $ million$)0\mathrm{.}010\mathrm{.}700\mathrm{.}901\mathrm{.}151\mathrm{.}301\mathrm{.}501\mathrm{.}70$

Probability of Financial Distress $0\mathrm{.}00\%0\mathrm{.}00\%1\mathrm{.}00\%2\mathrm{.}00\%7\mathrm{.}00\%16\mathrm{.}00\%31\mathrm{.}00\%$

Suppose the firm has a beta of zero, so that the appropriate discount rate for financial distress costs is the risk$-$free rate of $5\%.$ Which level of debt above is optimal if$,$ in the event of distress, the firm will have distress costs equal to $$2$ million?