#include
class A{
public:
A(int n = 0):m_n(n){
std::cout<<'a';
}
A(const A &a):m_n(a.m_n){
std::cout<<'b';
}
private:
int m_n;
};
void f(const A &a1,const A &a2 = A()){}
int main(){
A a(2),b;
const A c(a),&d = c,e = b;
b =d;
A *p = new A(c) , *q =& a;
static_cast<void>(q);
delete p;
f(3);
std::cout<<std::endl;
return 0;
}