foo.cc: In function 'int main()':
foo.cc:38:8: 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:43:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf ("%d%d",&u,&v);
   ~~~~~~^~~~~~~~~~~~~~
foo.cc:48:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf ("%d%d",&u,&v);
   ~~~~~~^~~~~~~~~~~~~~

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

{"receive":"2020-07-21T06:41:05.701Z","handle":"2020-07-21T06:41:05.701Z","cache_start":"2020-07-21T06:41:05.708Z","read_cases":"2020-07-21T06:41:05.835Z","judge":"2020-07-21T06:41:05.839Z","done":"2020-07-21T06:41:06.457Z"}