n = 50
z = 4
--------------------------------
function dig(n)
    sl = 2
    for i=1,n do
        while turtle.detect() do
            turtle.dig()
            sleep(sl)
        end
        turtle.digDown()
        turtle.digUp()
        turtle.back()
        while turtle.detect() do
            turtle.dig()
            sleep(sl)
        end
        turtle.forward()
        turtle.forward()
    end
end

function just_dig(n)
    for i=1,n do
        turtle.dig()
        turtle.forward()
    end
end
--------------------------------
dig(n)
--------------------------------
turtle.turnRight()
just_dig(z)
turtle.turnRight()
--------------------------------
dig(n)