# sub y{2021}

## --- Day 2: Dive! ---

Now, you need to figure out how to pilot this thing.

It seems like the submarine can take a series of commands like `forward 1`, `down 2`, or `up 3`:

• `forward X` increases the horizontal position by `X` units.
• `down X` increases the depth by `X` units.
• `up X` decreases the depth by `X` units.

Note that since you're on a submarine, `down` and `up` affect your depth, and so they have the opposite result of what you might expect.

The submarine seems to already have a planned course (your puzzle input). You should probably figure out where it's going. For example:

``````forward 5
down 5
forward 8
up 3
down 8
forward 2
``````

Your horizontal position and depth both start at `0`. The steps above would then modify them as follows:

• `forward 5` adds `5` to your horizontal position, a total of `5`.
• `down 5` adds `5` to your depth, resulting in a value of `5`.
• `forward 8` adds `8` to your horizontal position, a total of `13`.
• `up 3` decreases your depth by `3`, resulting in a value of `2`.
• `down 8` adds `8` to your depth, resulting in a value of `10`.
• `forward 2` adds `2` to your horizontal position, a total of `15`.

After following these instructions, you would have a horizontal position of `15` and a depth of `10`. (Multiplying these together produces `150`.)

Calculate the horizontal position and depth you would have after following the planned course. What do you get if you multiply your final horizontal position by your final depth?

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