Bridge

local x = 0
local depth = read()
for y = depth,1,-1 do
    x = x + 1
    for i = 1, 2, 1 do
        turtle.forward()
        turtle.placeDown()
        if i == 1 then
            turtle.turnRight()
        end
        if i == 2 then
            turtle.turnRight()
            turtle.turnRight()
            turtle.forward()
            turtle.turnRight()
        end
        for i = 16, 1, 1 do
            local data = turtle.getItemDetail(i)
            if data then
                if (data.name == "minecraft:cobblestone" or data.name == "minecraft:dirt" or data.name == "minecraft:stone") then
                    turtle.select(i)
                end
            end
        end
        turtle.select(1)
    end
    if (turtle.getFuelLevel() <= x + 5) then
        break
    end
end
turtle.turnRight()
turtle.turnRight()
for i = 1, x, 1 do
    turtle.forward()
end