foo.cc: In function 'int main()':
foo.cc:19:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     int n,m;scanf("%d%d",&n,&m);
             ~~~~~^~~~~~~~~~~~~~
foo.cc:27:64: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i=1;i<=m;i++) scanf("%d%d",&query[i].l,&query[i].r),query[i].index=i;
                           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~

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