foo.cc: In function 'int main()':
foo.cc:15:15: warning: 'w' may be used uninitialized in this function [-Wmaybe-uninitialized]
     int n,b,i,w,now,sum=0;
               ^

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