mine

function placeTorch()
 local item14 = turtle.getItemDetail(14)
 local item15 = turtle.getItemDetail(15)
 if (item14) and (item14.name == "minecraft:torch") then
  turtle.select(14)
  turtle.placeUp()
 elseif (item15) and (item15.name == "minecraft:torch") then
  turtle.select(15)
  turtle.placeUp()
 end
end

function excavate()
 turtle.dig()
 os.sleep()
 check = 1
 while check == 1 do
  local success, block = turtle.inspect()
  if block.name == "minecraft:gravel" then
   turtle.dig()
   os.sleep(0.5)
  else
   check=0
  end
 end
 turtle.forward()
 turtle.select(13)
 turtle.placeDown()
 turtle.digUp()
end

function digReturn()
 local torch = 0
 for i=1,len do
  excavate()
  torch = torch + 1
  if torch >= 10 then
   torch = 0
   placeTorch()
  end
 end
 placeTorch()
 turtle.turnLeft()
 turtle.turnLeft()
 for i=1,len do
  turtle.forward()
  check = 1
  while check == 1 do
   local success, block = turtle.inspect()
   if block.name ~= nil then
    turtle.dig()
    os.sleep(0.5)
   else
    check = 0
   end
  end
 end
end


local arg = {...}
num = tonumber(arg[1])
len = tonumber(arg[2])
turtle.turnLeft()
for a=1,num do
 digReturn()
 turtle.digDown()
 turtle.down()
 turtle.select(13)
 turtle.placeDown()
 turtle.up()
 turtle.select(16)
 turtle.placeDown()
 for i = 1,12 do
  turtle.select(i)
  turtle.dropDown()
 end
 turtle.select(1)
 digReturn()
 for i = 1,12 do
  turtle.select(i)
  turtle.dropDown()
 end
 turtle.select(1)
 turtle.turnRight()
 excavate()
 excavate()
 placeTorch()
 excavate()
 turtle.turnLeft()
end
turtle.turnRight()