What output will the program produce when run

Specify what text will appear in the console after executing the following code.

class A {
public:
    void f() { std::cout << "A"; }
};

class B : public A {
public:
    void f() { std::cout << "B"; }
};

void g(A &a) { a.f(); }

int main() {
    B b;
    g(b);
}