???????????????????????????????????????????????????

???????????????????????????μ???????????????????????????????????????????????????????????????????

??????????2???????

1??????????·??С??(9??????????)??????e?(599????????)?????????(1999????????)?????????(5999????????)????????(9999????????)?????????(99999????????)

2????????????????(9???????????)?????????(599????)?????????(1999????)?????????(5999????)?????????(9999????)??????????(99999????)

a????????