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;
}