function digF()
    while not turtle.forward() do
        turtle.dig()
    end
end

function digU()
    while not turtle.up() do
        turtle.digUp()
    end
end

function digD()
    while not turtle.down() do
        turtle.digDown()
    end
end

function detectU()
    while turtle.detectUp() do
        turtle.digUp()
    end
end

function detectD()
    while turtle.detectDown() do
        turtle.digDown()
    end
end

function tF()
    while turtle.getFuelLevel()==0  do
        turtle.refuel()
    end
end

function rL()
    while not turtle.detect() do
        turtle.turnLeft()
            while not turtle.detect()
                turtle.turnRight()
                turtle.turnRight()
            while not turtle.detect() do
                turtle.turnLeft()
                turtle.digF()
    else
        turtle.digF()
    end
end

function rR()
    while turtle.detectRight() do
        turtle.turnRight()
        turtle.dig()
    end
end

print("Enter lenght vaule of corridor")
local lenght=read()/2

for i=1,lenght do
tF()
digF()
detectD()
rL()
detectU()
digU()
digF()
end