The surface area of a sphere is calculated using the formula Surface Area $=(r^2)**4**,$ where $r$ is the sphere's radius.

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

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

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