print ackermann(1, 2)

function ackermann(m, n)
   if (m = 0)             then ackermann = (n + 1)
   if (m > 0) and (n = 0) then ackermann = ackermann((m - 1), 1)
   if (m > 0) and (n > 0) then ackermann = ackermann((m - 1), ackermann(m, (n - 1)))
end function