/in/foo.c:35:6: warning: return type of 'main' is not 'int' [-Wmain]
 void main()
      ^~~~
/in/foo.c: In function 'main':
/in/foo.c:48:1: error: expected declaration or statement at end of input
 }
 ^
/in/foo.c: In function 'prime':
/in/foo.c:31:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^