The probabilistic clock-synchronization protocol is efficient if many messages have a delay close to $\delta_{\min }$ (that is, $F\left(\delta_{\min }+\epsilon\right)$ moves away from 0 quickly even for small $\epsilon$ ).
Give a "dual" protocol that works efficiently if many messages have a delay close to $\delta_{\max }$ (that is, if $F\left(\delta_{\max }-\epsilon\right)$ stays sufficiently far from 1 even for small $\epsilon$ ). Show that the expected message complexity is $\left[1-F\left(\delta_{\max }-\epsilon\right)\right]^{-2}$ and give the expected running time.