foo.cc: In member function 'dts::ll dts::network_flows::bfs(dts::ll, dts::ll, double&, double&)':
foo.cc:99:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 for (ll i=0;i<cw[now].size();i++)
                             ~^~~~~~~~~~~~~~~
foo.cc: In function 'void dts::main()':
foo.cc:154:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
                     scanf("%lf",&v);
                     ~~~~~^~~~~~~~~~

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