Mã chấm: 268452

Main.cc: In function ‘int main()’:
Main.cc:9:10: error: ‘cin’ is not a member of ‘std’
     std::cin>>a>>b>>x>>y;
          ^~~
Main.cc:9:10: note: suggested alternative: ‘sin’
     std::cin>>a>>b>>x>>y;
          ^~~
          sin
Main.cc:10:10: error: ‘cout’ is not a member of ‘std’
     std::cout<