$105$
8. As shown in the figure, it is a rectangular prism with length, width, and height of $17 \mathrm{~cm}, 8 \mathrm{~cm}, 5 \mathrm{~cm}$ respectively. An ant starts from one vertex, crawling along the edges, with each edge being traversed at most once. The longest route the ant can crawl is $\qquad$ $\mathrm{cm}$.