void main()
    {
      clrscr();
      int x1,y1,x2,y2,sp,xmin,xmax,ymin,ymax;
      float kx,ky;
      cout<<"x1= "; cin>>x1;
      cout<<"y1= "; cin>>y1;
      cout<<"x2= "; cin>>x2;
      cout<<"y2= "; cin>>y2;
      sp=x1*y1+x2*y2;
      if(sp==0) cout<<"Vektora perpend.";
      else cout<<"Vertora ne perpend.";
      cout<<"\n";
      if(x1>=x2) {xmax=x1; xmin=x2;}
      else {xmax=x2; xmin=x1;}
      if(y1>=y2) {ymax=y1; ymin=y2;}
      else {ymax=y2; ymin=y1;}
      if(xmin!=0) kx=xmax/xmin;
      if(ymin!=0) ky=ymax/ymin;
      if(kx==ky) cout<<"Vektora kollinearnbl";
      else cout<<"Vektora ne kollinearnbl";
      getch();
    }