/in/foo.c: In function 'isPerfect':
/in/foo.c:18:5: warning: 'main' is normally a non-static function [-Wmain]
   18 | int main() {
      |     ^~~~
/in/foo.c:27:1: error: expected declaration or statement at end of input
   27 | }
      | ^
/in/foo.c:28: warning: control reaches end of non-void function [-Wreturn-type]
/in/foo.c: At top level:
/in/foo.c:18:5: warning: 'main' defined but not used [-Wunused-function]
   18 | int main() {
      |     ^~~~