foo.cc: In function 'int main()':
foo.cc:11:5: error: 'retuen' was not declared in this scope
     retuen 0;
     ^~~~~~
foo.cc:11:5: note: suggested alternative: 'freopen'
     retuen 0;
     ^~~~~~
     freopen

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