#include <iostream>
#include <cmath>
using namespace std;
struct circle{
    float x,y,r;
        void setCenter(float cx,float cy){
            x = cx;
            y = cy;
        }
        float getCenterX(){
            return x;
        }
        float getCenterY(){
            return y;
        }
        void setRadius(float rad){
            r = rad;
        }
       float getRadius(){
            return r;
        }
       float dist(circle c1){
           float d;
           d = sqrt((c1.x-x)*(c1.x-x)+(c1.y-y)*(c1.y-y))-c1.r-r;
           return d;
       }
};
int main()
{
    circle c1;
        c1.setCenter(4,6);
        c1.setRadius(3);
        cout<<"первый : "<<"x="<<c1.getCenterX()<<", y="<<c1.getCenterY()<<", r="<<c1.getRadius()<<endl;
    circle c2;
        c2.setCenter(9,4);
        c2.setRadius(5);
        cout<<"второй : "<<"x="<<c2.getCenterX()<<", y="<<c2.getCenterY()<<", r="<<c2.getRadius()<<endl;
cout<<c1.dist(c2)<<endl;

}