---

Lỗi biên dịch:

Main.cc: In function ‘int main()’:
Main.cc:9:13: error: ‘cin’ is not a member of ‘std’
        std::cin >> a >> b >> x >> y;
             ^~~
Main.cc:9:13: note: suggested alternative: ‘sin’
        std::cin >> a >> b >> x >> y;
             ^~~
             sin
Main.cc:10:13: error: ‘cout’ is not a member of ‘std’
        std::cout << a*x+b*y;
             ^~~~
Main.cc:10:13: note: suggested alternative: ‘cbrt’
        std::cout << a*x+b*y;
             ^~~~
             cbrt