The area of a circle is calculated using the formula Area $=(r^2)**,$ where $r$ is the circle's radius.

Given variable radius$\_$of$\_$circle read from input and constant PI$,$ compute the area of 'a circle and assign area$\_$of$\_$circle with the area.

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$\frac{?}{PI}=3\mathrm{.}14159$

radius$\_$of$\_$circle $=$ float input $()$