Поменять местами первую и последнюю букву местами в словах

unit Unit11;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
 
type
  TForm11 = class(TForm)
    ComboBox: TComboBox;
    Memo1: TMemo;
    Label1: TLabel;
    Label2: TLabel;
    Button1: TButton;
    procedure ComboBoxKeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form11: TForm11;
 
 
implementation
 
{$R *.dfm}
 
 
procedure ComboBoxKeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
var
  S : String;
  Ch : Char;
  i, Len, P1 : Integer;
begin
  S := Memo1.Text;
  Len := Length(S);
  P1 := 0;
  for i := 1 to Len do begin
 
    if S[i] in D then Continue;
 
    if (i = 1) or (S[i - 1] in D) then P1 := i;
 
    if (i = Len) or (S[i + 1] in D) then begin
 
      if i <> P1 then begin
        Ch := S[i];
        Delete(S, i, 1);
        Insert(Ch, S, P1);
      end;
    end;
  end;
 
  Memo1.Text := S;
end;
 
Procedure TForm1.Button1Click(Sender: TObject);
begin
Halt
end;
end.