local GRID_SIZE = 6

local function forward(times)
    for i = 1, times do
        turtle.forward()
    end
end

function grid_turn(isEvenRow)
    if isEvenRow then
        turtle.turnRight()
    else
        turtle.turnLeft()
    end
end


function check_grid()
    local isEvenRow = false

	turtle.forward()
    turtle.turnLeft()
    forward(2)
    turtle.turnLeft()
    for y = 1, GRID_SIZE do
        for x = 1, GRID_SIZE do
            turtle.suck()
            turtle.forward()
            turtle.suck()
        end
        if y < 6 then
            grid_turn(isEvenRow)
            turtle.suck()
            turtle.forward()
            turtle.suck()
            grid_turn(isEvenRow)
        end
        isEvenRow = not isEvenRow
    end
    turtle.turnLeft()
    forward(3)
end

check_grid()