foo.cc: In function 'int main()':
foo.cc:9:6: warning: unused variable 'xmin' [-Wunused-variable]
  int xmin,xmax,x;
      ^~~~
foo.cc:9:11: warning: unused variable 'xmax' [-Wunused-variable]
  int xmin,xmax,x;
           ^~~~

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