foo.cc: In function 'void dts::tr_dfs1(dts::ll, dts::ll)':
foo.cc:29:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (ll i=0;i<tr[now].s.size();i++)
                     ~^~~~~~~~~~~~~~~~~
foo.cc: In function 'void dts::tr_dfs2(dts::ll)':
foo.cc:41:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (ll i=0;i<tr[now].s.size();i++)
                     ~^~~~~~~~~~~~~~~~~
foo.cc: In function 'void dts::main()':
foo.cc:53:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld",&n);
         ~~~~~^~~~~~~~~~~
foo.cc:55:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%lld",&num[i]);
             ~~~~~^~~~~~~~~~~~~~~~
foo.cc:61:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%lld%lld%lld",&x,&y,&c);
             ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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