foo.c: In function 'main':
foo.c:33:5: warning: 'main' is normally a non-static function [-Wmain]
   33 | int main()
      |     ^~~~
foo.c: In function 'main':
foo.c:36:9: warning: implicit declaration of function 'scanf_s'; did you mean 'scanf'? [-Wimplicit-function-declaration]
   36 |         scanf_s("%d %d", &d1monht, &d1day);
      |         ^~~~~~~
      |         scanf
foo.c: At top level:
foo.c:33:5: warning: 'main' defined but not used [-Wunused-function]
   33 | int main()
      |     ^~~~

[Hydro](https://hydro.ac)提供评测服务