size = io.read()


function toChest()
    turtle.select(2)
    turtle.placeDown()
    for i = 3,16 do
        turtle.select(i)
        turtle.dropDown()
    end
    turtle.select(1)
    return true
    end
end

function refuel()
    turtle.select(3)
    for i = 3,16 do
        if i ~= 2 then
            turtle.select(i)
            turtle.refuel()
            end
        end
        turtle.select(3)
    end


function turn(flag)
    if flag == 1 then turtle.turnRight() end
    if flag == -1 then turtle.turnLeft() end
end
turtle.select(1)
turtle.refuel()


f = 1
for i = 1,size do
    for j = 1,size do



        if turtle.getFuelLevel() == 0 then refuel() end


        turtle.dig()
        turtle.digUp()
        turtle.digDown()
        if turtle.getItemCount(16) > 0 then toChest() end
        turtle.forward()


        end
    turn(f)
    turtle.dig()
    turtle.digUp()
    turtle.digDown()
    turtle.forward()
    turn(f)
    f = -f
    end