O: Yortp           

\: qsI(0,0)m@

m:
   1 UԦ\       Yе      -> I(0,0)
   2 uC                Y_yЦ   -> I(0,0)

: Enter yФؤo/Osnap/S ]w/?DU/I:

 1 Enter yФؤo - yФؤoIsI (k) 

 2 Osnap - ]wUHߦn (,,JI.....)

 3 S ]w -- wеeܧ.
         r  , C , r ,iۥѳ]w.
         ؤopI 0~4.
         r ---NrPеuZ.(uΤؤoѤr,еu,uզX)
         鶡 ---NPuZ.  
         wеuC,iN]w.
         wuC,iN]w.

 4 ?DU -- \ާ@.

 5 I -- ]wsI(0,0)m.
