答案三

class Point
{
public:
    Point(double x,double y,double z)
    {
        this->x=x;
        this->y=y;
        this->z=z;
    }
    Point(const Point& p)
    {
        this->x=p.x;
        this->y=p.y;
        this->z=p.z;
    }
    void negate()
    {
        x=-x;
        y=-y;
        z=-z;
    }
    double norm()
    {
        return sqrt(x*x+y*y+z*z);
    }
    void print()
    {
        cout<<x<<y<<z;
    }
private:
    double x,y,z;


};

class MyClass
{
public:
    MyClass(int xx=0,int yy=0)
    {
        X=xx;
        Y=yy;
    }
    MyClass(const MyClass & m);
private:
    int X,Y;
};
MyClass::MyClass(const MyClass & m)
{
    X=m.X;
    Y=m.Y;
}

long long solve(int n)
{
return pow(2.0,n+1)-1;
}