Mine^2

term.clear()
term.setCursorPos(1,1)

write("Distance: ")
input = read()
distance = tonumber(input)
i = 0
it = 0

while i < 4 do
    while it < distance do
        turtle.dig()
        turtle.forward()
        turtle.digUp()
        it = it + 1
    end
    it = it - 4
    i = i + 1
    turtle.turnLeft()
end