foo.cc:5:11: error: stray '\357' in program
 cout<<4*5=？<<endl;  
           ^
foo.cc:5:12: error: stray '\274' in program
 cout<<4*5=？<<endl;  
            ^
foo.cc:5:13: error: stray '\237' in program
 cout<<4*5=？<<endl;  
             ^
foo.cc: In function 'int main()':
foo.cc:5:14: error: expected primary-expression before '<<' token
 cout<<4*5=？<<endl;  
              ^~

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