阅读该程序，给出程序的输出结果。
#include <iostream.h>
class B
{
public:
B(int i,int j)
{
b1=i;
b2=j;
}
void Print()
{
cout<<b1<<','<<b2<<endl;
}
private:
int b1,b2;
};
class C
{
public:
C(int i)
{
c=i;
}
void Print()
{
cout<<c<<endl;
}
private:
int c;
};
class A
{
public:
A(int i,int j,int k, int l):c(i),b(j,k)
{
a=l;
}
void Print()
{
b.Print();
c.Print();
cout<<a<<endl;
}
private:
B b;
C c;
int a;
};
void main()
{
B b(7,8);
b.Print();
C c(9);
c.Print();
A a(4,5,6,7);
a.Print();
}
