foo.cc: In function 'int main()':
foo.cc:18:14: warning: 'sum' may be used uninitialized in this function [-Wmaybe-uninitialized]
   if(a[i])sum++;
           ~~~^~

正在同步测试数据，请稍后
自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。