\--- Day 23: Coprocessor Conflagration ---
----------

You decide to head directly to the CPU and fix the printer from there. As you get close, you find an *experimental coprocessor* doing so much work that the local programs are afraid it will [halt and catch fire](https://en.wikipedia.org/wiki/Halt_and_Catch_Fire). This would cause serious issues for the rest of the computer, so you head in and see what you can do.

The code it's running seems to be a variant of the kind you saw recently on that [tablet](18). The general functionality seems *very similar*, but some of the instructions are different:

* `set X Y` *sets* register `X` to the value of `Y`.
* `sub X Y` *decreases* register `X` by the value of `Y`.
* `mul X Y` sets register `X` to the result of *multiplying* the value contained in register `X` by the value of `Y`.
* `jnz X Y` *jumps* with an offset of the value of `Y`, but only if the value of `X` is *not zero*. (An offset of `2` skips the next instruction, an offset of `-1` jumps to the previous instruction, and so on.)

Only the instructions listed above are used. The eight registers here, named `a` through `h`, all start at `0`.

The coprocessor is currently set to some kind of *debug mode*, which allows for testing, but prevents it from doing any meaningful work.

If you run the program (your puzzle input), *how many times is the `mul` instruction invoked?*

Your puzzle answer was `9409`.

\--- Part Two ---
----------

Now, it's time to fix the problem.

The *debug mode switch* is wired directly to register `a`. You flip the switch, which makes *register `a` now start at `1`* when the program is executed.

Immediately, the coprocessor begins to overheat. Whoever wrote this program obviously didn't choose a very efficient implementation. You'll need to *optimize the program* if it has any hope of completing before Santa needs that printer working.

The coprocessor's ultimate goal is to determine the final value left in register `h` once the program completes. Technically, if it had that... it wouldn't even need to run the program.

After setting register `a` to `1`, if the program were to run to completion, *what value would be left in register `h`?*

Your puzzle answer was `913`.

Both parts of this puzzle are complete! They provide two gold stars: \*\*

At this point, all that is left is for you to [admire your Advent calendar](/2017).

If you still want to see it, you can [get your puzzle input](23/input).