foo.cc: In function 'int main()':
foo.cc:63:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
  ~~~~~^~~~~~~~~~
foo.cc:65:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lf%lf%lf%lf%lf",
   ~~~~~^~~~~~~~~~~~~~~~~~~~
     &wall[i].x, &wall[i].y[0], &wall[i].y[1], &wall[i].y[2], &wall[i].y[3]);
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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