foo.cc: In function 'int main()':
foo.cc:44:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf( "%d%d%d%d", &n, &m, &k1, &k2 );
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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

{"receive":"2020-05-29T12:23:11.876Z","handle":"2020-05-29T12:23:11.876Z","cache_start":"2020-05-29T12:23:11.882Z","read_cases":"2020-05-29T12:23:12.483Z","judge":"2020-05-29T12:23:12.484Z","done":"2020-05-29T12:23:14.074Z"}