PUZZLE 146 River Crossing

Use the sandbags as stepping stones to get across the river.
The numbers represent the depth of the water, and you need that number of sandbags to cross that part of the river.
What would be the minimum number of sandbags you would need to cross from one side of the river to the other?
You are not allowed to move diagonally.

Hint 1

Look for a route that uses the smallest number of sandbags.
You'll want to avoid the places that are '5' deep.

Hint 2

The route has just one section that is '1' deep.
You don't need to pass through a section that is '4' deep.

Hint 3

You've found the shortest route now, but placing that number of sandbags along it is not the correct answer.
You're not trying to build a path that others can use after you, so you just need to think about how to get yourself across.

Super Hint

As you cross the river, you can reach from the sandbag you are standing on to reuse sandbags you have already crossed.
Then you won't need to use as many. First use some sandbags to cross the '3' and '2' on the right-hand side.

Answer for 'River Crossing'

The answer is '5'.