Lua Slot machine

local Letters = {"@","&","?","@","&","$","@","&","?","@","$","&","@","?","7"}
local Data = {}
local TSize = table.getn(Letters)
local MinNumbersOfSpin = 15
local MaxNumbersOfSpin = 20

mon = peripheral.wrap( "back" )
mon.clear()

function writeString(String,X,Y)
    mon.setCursorPos(X,Y)
    mon.write(String)
end

function spinSlot(Slot)
    Data[Slot][4] =  Data[Slot][4] > 1 and Data[Slot][4] - 1 or TSize

    local ID = Data[Slot][4]
    local X = 3+6*(Slot-1)

    Data[Slot][1] = Letters[ID > 1 and ID-1 or TSize]
    Data[Slot][2] = Letters[ID]
    Data[Slot][3] = Letters[ID < TSize and ID+1 or 1]

    writeString(Data[Slot][1],X,2)
    writeString(Data[Slot][2],X,3)
    writeString(Data[Slot][3],X,4)
end

writeString("+---+ +---+ +---+",1,1)
writeString("|   | |   | |   |",1,2)
writeString("|[ ]| |[ ]| |[ ]|",1,3)
writeString("|   | |   | |   |",1,4)
writeString("+---+ +---+ +---+",1,5)

for i = 1,3 do
    table.insert(Data,{})
    Data[i][4] = math.random(1,TSize)
    spinSlot(i)
end

function roll()
    writeString("                 ",1,8)
    writeString("                 ",1,9)

    MaxTurns1 = math.random(MinNumbersOfSpin ,MaxNumbersOfSpin)
    MaxTurns2 = math.random(MaxTurns1+MinNumbersOfSpin-6 ,MaxTurns1+MaxNumbersOfSpin-6)
    MaxTurns3 = math.random(MaxTurns2+MinNumbersOfSpin-10 ,MaxTurns2+MaxNumbersOfSpin-10)

    for NumberOfTurn=1, MaxTurns3 do
        if NumberOfTurn <= MaxTurns1 then spinSlot(1) end
        if NumberOfTurn <= MaxTurns2 then spinSlot(2) end
        if NumberOfTurn <= MaxTurns3 then spinSlot(3) end
        os.sleep(0.03+NumberOfTurn/250)
    end

    if Data[1][2] == Data[2][2] and Data[2][2] == Data[3][2] then
        writeString("!Congratulations!",1,8)
        writeString("You won",6,9)
    else
        writeString("Sorry :(",6,8)
        writeString("You lose",6,9)
    end
end

while true do
    local event, p1, p2 = os.pullEvent()
    if event == "redstone" then
        if rs.getInput("right") then
            roll()
        end
    end
end