Вывести по нажатию кнопки рандомный круг с рандомным цветом

{$apptype windows}
{$reference 'System.Windows.Forms.dll'}
{$reference 'System.Drawing.dll'}
 
uses
  System.Windows.Forms;
 
 
var
  MainForm: System.Windows.Forms.Form;
  B1: System.Windows.Forms.Button;
  
  
  a, b: byte; z, x, c, v: System.Drawing.Brush;
 
procedure  ellipse1(sender: object; Graf1: System.Windows.Forms.PaintEventArgs);
begin
  Graf1.Graphics.FillEllipse(z, 170, 10, 50, 50);
end;
 
procedure ellipse2(seder: object; Graf2: System.Windows.Forms.PaintEventArgs);
begin
  Graf2.Graphics.FillEllipse(x, 250, 10, 50, 50);
end;
 
procedure ellipse3(seder: object; Graf3: System.Windows.Forms.PaintEventArgs);
begin
  Graf3.Graphics.FillEllipse(c, 170, 60, 50, 50);
end;
 
procedure ellipse4(seder: object; Graf4: System.Windows.Forms.PaintEventArgs);
begin
  
  Graf4.Graphics.FillEllipse(v, 250, 60, 50, 50); 
  
  
end;
 
procedure q(Sender: Object; Args: System.Windows.Forms.PaintEventArgs);
begin
  if a = 0 then begin
    if (b = 0) then begin z := System.Drawing.Brushes.red; end else 
    if (b = 1) then begin z := System.Drawing.Brushes.yellow; end else
    if (b = 2) then begin z := System.Drawing.Brushes.green;  end else
    if (b = 3) then begin z := System.Drawing.Brushes.blue; end; end;
  a := -1; b := -1;MainForm.Paint += ellipse1;
end;
 
procedure w(Sender: Object; Args: System.Windows.Forms.PaintEventArgs);
begin
  if a = 1 then begin
    if (b = 0) then begin x := System.Drawing.Brushes.red;  end else
    if (b = 1) then begin x := System.Drawing.Brushes.yellow;  end else
    if (b = 2) then begin x := System.Drawing.Brushes.green;  end else
    if (b = 3) then begin x := System.Drawing.Brushes.blue;  end; end; MainForm.Paint += q;
  a := -1; b := -1;MainForm.Paint += ellipse2;
end;
 
procedure e(Sender: Object; Args: System.Windows.Forms.PaintEventArgs);
begin
  if a = 2 then begin
    if (b = 0) then begin c := System.Drawing.Brushes.red;  end else
    if (b = 1) then begin c := System.Drawing.Brushes.yellow;  end else
    if (b = 2) then begin c := System.Drawing.Brushes.green;  end else
    if (b = 3)  then begin c := System.Drawing.Brushes.blue;  end; end;
  a := -1; b := -1;MainForm.Paint += ellipse3;
end;
 
procedure r(Sender: Object; Args: System.Windows.Forms.PaintEventArgs);
begin
  if a = 3 then begin
    if (b = 0) then begin v := System.Drawing.Brushes.red;  end else
    if (b = 1) then begin v := System.Drawing.Brushes.yellow;  end else
    if (b = 2) then begin v := System.Drawing.Brushes.green;  end else
    if (b = 3) then begin v := System.Drawing.Brushes.blue;  end; end; MainForm.Paint += e;
  a := -1; b := -1;MainForm.Paint += ellipse4;
end;
 
 
 
 
 
 
 
 
 
 
procedure B1_Click(Sender: Object; Args: System.EventArgs);
var
  a1, b1: byte;
begin
  z := System.Drawing.Brushes.White;
  x := System.Drawing.Brushes.White;
  c := System.Drawing.Brushes.White;
  v := System.Drawing.Brushes.White;
  
  randomize;
  
  a1 := random(4);
  b1 := random(4);
  a := a1; b := b1;if (a = 3) or (a = 2) then MainForm.Paint += r else if (a = 1) or (a = 0) then MainForm.Paint += w;
  {if a = 0 then  MainForm.Paint+= q else 
  
  if a = 1 then  MainForm.Paint+= w else
  
  if a = 2 then  MainForm.Paint+= e else
  
  if a = 3 then  MainForm.Paint+= r ;} writeln(a, ' ', b);
  
  MainForm.Refresh;
end;
 
 
 
 
 
begin
  
  
  
  
  z := System.Drawing.Brushes.White;
  x := System.Drawing.Brushes.White;
  c := System.Drawing.Brushes.White;
  v := System.Drawing.Brushes.White;
  B1 := new Button;
  B1.Location := new System.Drawing.Point(110, 140);
  B1.Text := 'Кнопка';
  B1.Click += B1_Click;
  
  
  
  
  MainForm := new Form;
  MainForm.Text := 'Form';
  MainForm.ClientSize := new System.Drawing.Size(500, 500);
  MainForm.BackColor := system.Drawing.Color.White; 
  MainForm.StartPosition := FormStartPosition.CenterScreen;
  MainForm.MaximizeBox := false;
  MainForm.Controls.Add(B1);
  MainForm.Paint += ellipse1;
  MainForm.Paint += ellipse2;
  MainForm.Paint += ellipse3;
  MainForm.Paint += ellipse4;
  Application.EnableVisualStyles;
  
  Application.Run(MainForm);
  
  
end.