Main.c: In function 'calculateVolume':
Main.c:17:26: error: 'M_PI' undeclared (first use in this function)
   17 |     return (4.0 / 3.0) * M_PI * pow(radius, 3);
      |                          ^~~~
Main.c:17:26: note: each undeclared identifier is reported only once for each function it appears in
Main.c:18:1: warning: control reaches end of non-void function [-Wreturn-type]
   18 | }
      | ^