StairCirLi

function turn()
    turtle.turnRight()
end

function TestGraSa()
    while turtle.detect(gravel) == true do
        turtle.dig()
    end
    while turtle.detect(sand) == true do
        turtle.dig()
    end
end

function TestFront()
    if turtle.detect() == false then
        os.exit()
    end
end

function Stair()
    for i = 1,3 do
        turtle.dig()
        TestGraSa()
        turtle.digDown()
        turtle.down()
        turtle.dig()
        TestGraSa()
        turtle.forward()
        TestFront()
    end
    turn()
 Torch()
end

function Torch()
  turtle.select(16)
  turtle.placeUp()
  turtle.select(1)
end

print("Depth: ")
local k = read()

for i = 1,k do
    Stair()
end