帮忙看看问题出在哪里 关于运算符重载

#include<iostream>
using namespace std;
class Point
{
    int x,y;
public:
    void set(int a,int b)
    {
        x=a;y=b;
    }
    void print() const
    {
        cout<<"x="<<x<<' '<<"y="<<y<<endl;
    }
    friend  Point operator+(const Point& a,const Point& b);
    friend   Point add(const Point& a, const Point& b);

};
  Point add(const Point& a, const Point& b)
{
    Point s;
    s.set(a.x+b.x,a.y+b.y);
    return s;
}
 Point operator +(const Point& a,const Point& b)
{
    Point s;
    s.set(a.x+b.x,a.y+b.y);
    return s;
}
int main()
{
    Point a,b;
    a.set(3,2);
    b.set(1,5);
    (a+b).print();
    operator+(a,b).print();
    add(a,b).print();

}