function split(str, ts)
  -- 引数がないときは空tableを返す
  if ts == nil then return {} end
  local t = {} ;
  i=1
  for s in string.gmatch(str, "([^"..ts.."]+)") do
    t[i] = s
    i = i + 1
  end
  return t
end

local function write1()
    local f = io.open("last.dat", "w")
    f:write("1,2,3,N")
    f:close()
end

local function write2()
    local f = io.open("last.dat", "w")
    f:write("3,2,1,N")
    f:close()
end

local function read()
    local f = io.open("last.dat", "r")
    for line in f:lines() do
        local strs = split(line, ",")
        for i = 1, #strs do
            print(strs[i])
        end
    end
    f:close()
end

local quitFlag = false

local function quitProcess()
    local event, param1 = os.pullEvent()
    if param1 == "q" then
        write2()
        quitFlag = true
    end
end

while not quitFlag do
    parallel.waitForAny(quitProcess)
    read()
    os.sleep(0.05)
end