foo.cc: In function 'int main()':
foo.cc:9:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&w,&n);
  ~~~~~^~~~~~~~~~~~~~
foo.cc:11:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",wi+i,vi+i);
   ~~~~~^~~~~~~~~~~~~~~~~~

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