c++习题1_B_c++继承改错

/*
*作者：lws
*完成时间：2014/6/12
*输入：1 2 3 4 5
*输出：a:3 b:4 a:3 b:4 c:5
*/
#include <iostream>
using namespace std;
class A
{
public:
A(int aa,int bb){a=aa,b=bb;}
void printA()
{
cout<<"a:"<<a<<"b:"<<b<<endl;
}
protected://改之前为private
int a,b;
};
class B:public A
{
public:
B(int aa,int bb,int cc)/*{a=aa;b=bb;c=cc;}*/:A(aa,bb),c(cc){}
void printB()
{
cout<<"a:"<<a<<"b:"<<b<<"c:"<<c<<endl;
}
private:
int c;
};
int main()
{
int a1,a2;
int b1,b2,b3;
cin>>a1>>a2;
cin>>b1>>b2>>b3;
A a(a1,a2);
B b(b1,b2,b3);
a=b;
a.printA();
b.printB();
return 0;
}