-- $Id: ackermann.lua,v 1.5 2000/12/09 20:07:43 doug Exp $
-- http://www.bagley.org/~doug/shootout/

local function Ack(M, N)
    if (M == 0) then
        return N + 1
    end
    if (N == 0) then
        return Ack(M - 1, 1)
    end
    return Ack(M - 1, Ack(M, (N - 1)))
end

N = tonumber((arg and arg[1])) or 3
M = tonumber((arg and arg[2])) or 8
print(string.format("Ack(%d, %d) = %d\n", N, M, Ack(N,M)))