#include<iostream>
#include <memory>
using namespace std;
class pointer
{
   
    public:
    int x,y;
    pointer(int a,int b):x(a),y(b){}
};
class Circle
{
    public:
    int radius;
    int centerx;
    int centery;
    Circle(int a,int b,int c):centerx(a),centery(b),radius(c){}
    public:
    void isPoinrterinCircle(pointer&p)
    {
        int d=(p.x-centerx)*(p.x-centerx)+(p.y-centery)*(p.y-centery);
        if(d<radius*radius)
        {
            cout<<"in"<<endl;
        }
         else if(d==radius*radius)
         {
            cout<<"on"<<endl;
        }
         else
         {
            cout<<"out"<<endl;
         }
    }
};
void test01()
{
    int a,b;
    cin>>a>>b;
    pointer p(a,b);
    Circle c1(5,0,5);

    c1.isPoinrterinCircle(p);
    
}
int main()
{
    test01();
    return 0;
}

自己瞎写,适当参考