foo.cc: In function 'bool check(long long int)':
foo.cc:17:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(ll i=0; i<edge[x].size(); i++){
                 ~^~~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:54:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld %lld %lld",&n,&s,&m);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:57:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld %lld %lld",&x,&y,&z);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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