#include <iostream>
using namespace std;

struct A {
    char a;
    A(char aa = 'a') {
        a = aa;
    }

    A& operator=(const A& aa) {
        a = aa.a;
        cout << "A::operator=()\n";
        return *this;
    }
};

struct B: public A {
    char b;
    B(char bb = 'b') : A(bb) {
        b = bb;
    }
};

int main() {
    B b1(1),b2(2);
    b1 = b2;
}