foo.cc: In function 'int floyd()':
foo.cc:44:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
foo.cc: In function 'int main()':
foo.cc:66:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  freopen("a.in","r",stdin);
  ~~~~~~~^~~~~~~~~~~~~~~~~~
foo.cc:69:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d",&n,&m1,&m2);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~
foo.cc:75:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&x,&y);
   ~~~~~^~~~~~~~~~~~~~
foo.cc:80:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&x,&y);
   ~~~~~^~~~~~~~~~~~~~

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

{"receive":"2020-07-21T06:59:44.537Z","handle":"2020-07-21T06:59:44.537Z","cache_start":"2020-07-21T06:59:44.546Z","read_cases":"2020-07-21T06:59:44.690Z","judge":"2020-07-21T06:59:44.690Z","done":"2020-07-21T06:59:45.101Z"}