PUZZLE 179 Alien Attack 2

Use a special beam cannon to wipe out the fleet of UFOs that have appeared over the streets of London.
Each UFO has a number on it, and this is the number of times you must hit it to destroy it.
All UFOs must be destroyed.
Each beam has enough energy to travel along one line only.
You can choose the direction o the beam, but you cannot travel along the same line twice.
To fire, touch where you would like the beam to travel.

Hint 1

Let's think about the UFO with the '4' on it a little later.
First, fire the cannon straight up, then through the UFO located diagonally up and right from the start point.
Next, proceed until the beam is just to the left of the UFO at the bottom-right corner, being sure to pass through the bottom-centre UFO on the way.

Hint 2

Continuing on from hint one...
Then, carry out repeated attacks on the UFO directly above with the '3' on it, firing from below and from the left.
When this UFO is destroyed, set your sights on the central UFO with the '3' on it.

Hint 3

Continuing on from hint two...
Go down from the middle point and then fire a beam through the central UFO from the left, before then attacking the UFO on the right-hand edge.
Then proceed to the top-right corner.

Super Hint

Continuing on from hint three...
Take the upper line from the top-right corner and continue until you are above the UFO with the '4' on it.
Then carry out a concentrated attack on that UFO, destroying the UFOs around it in the meantime.

Answer for 'Alien Attack 2'

The answer is as follows.

up, right, right, down, right,
up, up, down-left, right, right,
down, up-left, up-left, down, down-left,
up, up, right, right, up-right,
up, left, left, left, down,
up-left, down, right, down-left, right,
up, down-right, up, left, up-right,
down, right, down-right.