Mã chấm: 452181

Main.cc: In function ‘int main()’:
Main.cc:8:18: error: ‘cin’ was not declared in this scope; did you mean ‘sin’?
    8 |     int a,b,c,d; cin >> a >> b >> c >> d;
      |                  ^~~
      |                  sin
Main.cc:9:5: error: ‘cout’ was not declared in this scope
    9 |     cout << (a * x) + (b * y);
      |     ^~~~
Main.cc:9:18: error: ‘x’ was not declared in this scope
    9 |     cout << (a * x) + (b * y);
      |                  ^
Main.cc:9:28: error: ‘y’ was not declared in this scope
    9 |     cout << (a * x) + (b * y);
      |                            ^