下面代码执行后的输出结果为（ ）。
#include <iostream>
#include <cmath> using namespace std;
class Point {
public:
Point(int X=0, int Y=0); Point(Point &p);
int GetX() {return X;} int GetY() {return Y;}
static int countP;
static void GetC(Point A,Point B) {
int z; z=sqrt((B.X-A.X)*(B.X-A.X)+(B.Y-A.Y)*(B.Y-A.Y)); cout<<z<<endl;
}
private: int X,Y;
};
Point::Point(int X, int Y) {
this->X=X;this->Y=Y;
countP++; }
Point::Point(Point &p) {
X=p.X; Y=p.Y; countP++;
}
int Point::countP=0;
int main() {
Point D(3,4),*p;
Point E(D);
p=&E;
void (*q)(Point,Point)=Point::GetC; (*q)(D,E);
return 0; }