#include <iostream>
#include <cmath>
 
using namespace std;
 
class Point
{
public:
   Point();
   Point ( int x, int y );
   int X() const;
   int Y() const;
   void SetX ( int );
   void SetY ( int );
 
private:
   int m_X;
   int m_Y;
};
 
// point.cpp
Point::Point()
{}
 
Point::Point ( int x, int y ) : m_X ( x ), m_Y ( y )
{}
 
int Point::X() const
{
   return m_X;
}
int Point::Y() const
{
   return m_Y;
}
void Point::SetX ( int x )
{
   m_X = x;
}
void Point::SetY ( int y )
{
   m_Y = y;
}
 
// line.h
class Line
{
public:
   Line ( const Point&, const Point& );
   Point StartPoint() const;
   Point EndPoint() const;
   void SetStartPoint ( const Point& );
   void SetEndPoint ( const Point& );
   double Length() const;
 
private:
   Point m_StartPoint;
   Point m_EndPoint;
};
 
Line::Line (
   const Point& start,
   const Point& end ) : m_StartPoint ( start ), m_EndPoint ( end )
{}
 
Point Line::StartPoint() const
{
   return m_StartPoint;
}
Point Line::EndPoint() const
{
   return m_EndPoint;
}
void Line::SetStartPoint ( const Point& start )
{
   m_StartPoint = start;
}
void Line::SetEndPoint ( const Point& end )
{
   m_EndPoint = end;
}
double Line::Length() const
{
   int diffX = m_EndPoint.X() - m_StartPoint.X();
   int diffY = m_EndPoint.Y() - m_StartPoint.Y();
   return sqrt ( double ( diffX*diffX + diffY*diffY ) );
}
 
 
int main()
{
    Point a(4,3);
    //a.SetX(4);
    //a.SetY(3);
 
    Point b(2,1);
    //b.SetX(2);
    //b.SetY(1);
 
    Line myLine(a,b);
    cout << myLine.Length();
    cout << "\n";
 
    system("pause");
}