ItemCounter ComputerCraft

mon = peripheral.find("monitor")



inSize = chest.size()

chest = peripheral.find("minecraft:chest")

x,y = mon.getSize()

monCenter = (x/2 + y/2)/2

slot = 0

currentItems = 0
maxItems = 0

while true do
    if slot >= inSize then
        mon.setBackgroundColor(colors.gray)
        mon.setTextColor(colors.red)
        slot = slot - slot
        mon.write(currentItems.. "/" ..maxItems)
        sleep(15)
    end

    slot = slot + 1
    item = chest.getItemDetail(slot)
    itemlimit = chest.getItemLimit(slot)
    mon.setBackgroundColor(colors.black)
    mon.setTextColor(colors.white)
    mon.setCursorPos(monCenter)
    mon.write("Counting...")
    currentItems = CurrentItems + item.count
    maxItems = maxItems + itemlimit
    sleep(1)
end