#include <iostream>
using std::cout;
using std::endl;
 
struct IB {
	virtual void b() = 0;
};
 
struct B : IB {
	void b() override { cout << "B::b" << endl; }
};
 
struct IA {
	virtual void a() = 0;
};
 
struct A : IA, B {
	void a() override { cout << "A::a" << endl; }
};
 
struct IAB : IA, IB {
	IAB(IA *ia, IB *ib) : ia(ia), ib(ib) {}
	void a() override { ia->a(); }
	void b() override { ib->b(); }
private:
	IA *ia;
	IB *ib;
};
 
int main() {
	A a;
	IAB iab(&a, &a);
	iab.a();
	iab.b();
}

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