procedure TForm1.Button1Click(Sender: TObject);
var
s,s1:string;
i,j:integer;
begin
s:='20,30,40,50';
i:=length(s);
for j:=0 to i-1 do
begin
if s[j]=',' then
begin
s1:=s[j-2]+s[j-1];
showmessage(s1);
end;
end;
if s[i]<>',' then
begin
s1:=s[i-1]+s[i];
showmessage(s1);
end
else
begin
s1:=s[j-2]+s[j-1];
showmessage(s1);
end;
end;