{$n+}
uses graph;

const
  dT = 1;
  Vz = 5;
  Vs = 10;

type
  TPoint = record
    X, Y: double;
  end;

procedure ShowPoint(P: TPoint; color: integer);
begin
  setcolor(color);
  {
  Circle(Trunc(P.X), Trunc(P.Y), 2);
  }
  LineTo(Trunc(P.X), Trunc(P.Y));
end;

var
  Pz, Ps: TPoint;

var
  dx, dy, r: double;
  gd, gm: integer;
  i: integer;

begin
  gd := detect;
  initgraph(gd, gm, '');
  if graphresult <> grok then begin
    writeln('Error...'); halt(100)
  end;

  Pz.X := 0; Pz.Y := GetMaxY;
  Ps.X := 400; Ps.Y := GetMaxY;

  for i := 1 to 30 do begin
    moveto(Trunc(Pz.X), Trunc(Pz.Y));
    Pz.X := Pz.X + (Vz * dT * sin(45*Pi/180));
    Pz.Y := Pz.Y - (Vz * dT * sin(45*Pi/180));
    ShowPoint(Pz, white);

    dx := Pz.X - Ps.X;
    dy := Pz.Y - Ps.Y;
    r := sqrt(sqr(dx)+sqr(dy));

    moveto(Trunc(Ps.X), Trunc(Ps.Y));
    Ps.X := Ps.X + dx * Vs * dT / r;
    Ps.Y := Ps.Y + dy * Vs * dT / r;
    ShowPoint(Ps, red);
  end;
  readln;

  closegraph;

end.