foo.cc: In function 'int main()':
foo.cc:31:14: warning: 'y' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<x<<" "<<y;
  ~~~~~~~~~~~~^~~
foo.cc:31:11: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<x<<" "<<y;
           ^~~

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