Ag~1?Lp1~2@g'p?g?Pf1FJ                               Ackermann function.  if m=0 => run Ackermann function (m, n+1)
      xI;    x@g'p??@Mf1fFJ                                               if m>0 and n=0 => run Ackermann (m-1,1)
                 xM@~gM??f~f@f1FJ                                         if m>0 and n>0 => run Ackermann(m,Ackermann(m-1,n-1))
_ii1FJ                                               input function. Input m,n, then execute Ackermann(m,n)