KöMaL 2011 K315

Let $\downarrow n \downarrow$ denote the greatest prime number smaller than $n$, and let $\uparrow n \uparrow$ denote the smallest prime greater than $n$. Calculate the value of the expression $41+ \downarrow 35 \downarrow - \uparrow 53 \uparrow + \big\uparrow \downarrow 40 \downarrow \big\uparrow$.