procedure TForm2.Button3Click(Sender: TObject);
var
s : string;
result : string;
i : Byte;
begin
s := '''idi'': ''7841671'',';
s := Copy(S, Pos('idi''', S)+7);
for I := 1 to Length(s) do
if (Ord(s[i]) >= 48) and (Ord(s[i]) <= 57) then
result := result + s[i]
else
Break;
ShowMessage(result);
end;