/in/foo.c: In function 'prime':
/in/foo.c:25:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/foo.c: In function 'superprime':
/in/foo.c:37:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^