квадрат 2

#include <iostream>
#include <cmath>

using namespace std;

struct otrezok
{
  public:
  double x1, y1, x2, y2, x, y;
  double length;
};

struct vershina
{
  double x, y;
};

otrezok vector (vershina head, vershina seredina)
{
 otrezok time;

   time.x1 = head.x;
   time.y1 = head.y;
   time.x2 = seredina.x;
   time.y2 = seredina.y;

   time.x = time.x2 - time.x1;
   time.y = time.y2 - time.y1;

 double znach = time.x;

 time. x = time.y;

 if (znach != 0)
 time.y = -znach;
 else time.y = znach;
 //cout << time.x << " " << time.y << endl;
 time.x1 = time.x2 - time.x;
 time.y1 = time.y2 - time.y;
 return time;
}

int main ()
{
  vershina A, C;
  cin >> A.x >> A.y >> C.x >> C.y;
  otrezok AC, DB;

  vershina seredina_AC;

  seredina_AC.x = (A.x + C.x)/2;
  seredina_AC.y = (A.y + C.y)/2;

  AC = vector (A, seredina_AC);
  DB = vector (C, seredina_AC);


  cout << AC.x1 << " " << AC.y1 << endl;
  cout << DB.x1 << " " << DB.y1 << endl;
}