foo.cc: In function 'int main()':
foo.cc:39:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d",&n,&m);
     ~~~~~^~~~~~~~~~~~~~
foo.cc:42:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&s,&t);
         ~~~~~^~~~~~~~~~~~~~

自豪的采用 HydroJudge 进行评测(github.com/hydro-dev/HydroJudge)

{"receive":"2020-07-14T11:48:53.629Z","handle":"2020-07-14T11:48:53.631Z","cache_start":"2020-07-14T11:48:53.719Z","read_cases":"2020-07-14T11:48:53.978Z","judge":"2020-07-14T11:48:53.984Z","done":"2020-07-14T11:48:56.611Z"}