bridge

function findMaterial()
    if turtle.getItemCount() > 0 then
        return
    end

    for i = 1, 16, 1 do
        turtle.select(i)
        local count = turtle.getItemCount()
        if count > 0 then
            return
        end
    end
end

local length = 0;

while not turtle.detect() do
    findMaterial()
    turtle.placeDown()
    if turtle.forward() then
        length = length + 1
    end
end

for i = 1, length, 1 do
    turtle.back()
end