关于析构函数

class Point
{
public:
Point(int xx=0, int yy=0) {X=xx; Y=yy; countP++; }
Point(Point &p);
~Point(){ countP--;}

int GetX() {return X;}
int GetY() {return Y;}
void GetC() {cout<<" Object id="<<countP<<endl;}
private:
int X,Y;
static int countP;
};
Point::Point(Point &p)
{
X=p.X;
Y=p.Y;
countP++;
}

int Point::countP=0;
int main()
{
Point A(4,5);
cout<<"Point A,"<<A.GetX()<<","<<A.GetY();
A.GetC();
Point B(A);
cout<<"Point B,"<<B.GetX()<<","<<B.GetY();
B.GetC();
}
红色的一句是干什么的呢，为什么在此句中加上输出，会输出一个莫名其妙的countP