#include"iostream.h"
#include"math.h"
class line;
class point()
{
private:
double x,y;
public:
point (double x1,double y1)
{
x=x1;
y=y1;
}
friend double dist(point,line);
};
class line()
{
private:
double a,b,c;
public:
line(double a1,double b1,double c1)
{
a=a1;
b=b1;
c=c1;
}
friend double dist(point,line);
};
double dist(point p1,point p2)
{
double d,d1,d2;
d1=p2.a*p1.x+p2.b*p1.y+p2.c;
d2=sqrt(p2.a*p2.a+p2.b*p2.b);
d=fabs(d1/d2);
return d;
}
void main()
{
point p1(4,5);
line p2(1,2,4);
cout<<dist(p1,p2)<<endl;
}