编写派生类构造函数使其运行结果为“AB”

基类中有两个构造函数，一个无参，一个有参。
#include
using namespace std;
class Base {
protected:
Base() { cout << 'A'; }
Base(char c) { cout << c; }
};
class Derived :public Base {
public:

//    

};
int main() {
Derived d1('B');
return 0;
}

#include<iostream>
using namespace std;

class Base {
protected:
    Base() { cout << 'A'; }
    Base(char c) { cout << c; }
};
class Derived :public Base {
public:
    Derived() { cout << 'B'; }
    Derived(char c) { cout << c; }
};
int main() {
    Derived d1('B');
    //Derived
    return 0;
}