## \-\-- Day 4: Ceres Search \-\--

\"Looks like the Chief\'s not here. Next!\" One of The Historians pulls
out a device and pushes the only button on it. After a brief flash, you
recognize the interior of the [Ceres monitoring station](/2019/day/10)!

As the search for the Chief continues, a small Elf who lives on the
station tugs on your shirt; she\'d like to know if you could help her
with her *word search* (your puzzle input). She only has to find one
word: `XMAS`.

This word search allows words to be horizontal, vertical, diagonal,
written backwards, or even overlapping other words. It\'s a little
unusual, though, as you don\'t merely need to find one instance of
`XMAS` - you need to find *all of them*. Here are a few ways `XMAS`
might appear, where irrelevant characters have been replaced with `.`:

    ..X...
    .SAMX.
    .A..A.
    XMAS.S
    .X....

The actual word search will be full of letters instead. For example:

    MMMSXXMASM
    MSAMXMSMSA
    AMXSXMAAMM
    MSAMASMSMX
    XMASAMXAMM
    XXAMMXXAMA
    SMSMSASXSS
    SAXAMASAAA
    MAMMMXMMMM
    MXMXAXMASX

In this word search, `XMAS` occurs a total of `18` times; here\'s the
same word search again, but where letters not involved in any `XMAS`
have been replaced with `.`:

    ....XXMAS.
    .SAMXMS...
    ...S..A...
    ..A.A.MS.X
    XMASAMX.MM
    X.....XA.A
    S.S.S.S.SS
    .A.A.A.A.A
    ..M.M.M.MM
    .X.X.XMASX

Take a look at the little Elf\'s word search. *How many times does
`XMAS` appear?*

Your puzzle answer was `2378`.

## \-\-- Part Two \-\-- {#part2}

The Elf looks quizzically at you. Did you misunderstand the assignment?

Looking for the instructions, you flip over the word search to find that
this isn\'t actually an `XMAS` puzzle; it\'s an
`X-MAS`
puzzle in which you\'re supposed to find two `MAS` in the shape of an
`X`. One way to achieve that is like this:

    M.S
    .A.
    M.S

Irrelevant characters have again been replaced with `.` in the above
diagram. Within the `X`, each `MAS` can be written forwards or
backwards.

Here\'s the same example from before, but this time all of the `X-MAS`es
have been kept instead:

    .M.S......
    ..A..MSMS.
    .M.S.MAA..
    ..A.ASMSM.
    .M.S.M....
    ..........
    S.S.S.S.S.
    .A.A.A.A..
    M.M.M.M.M.
    ..........

In this example, an `X-MAS` appears `9` times.

Flip the word search from the instructions back over to the word search
side and try again. *How many times does an `X-MAS` appear?*

Your puzzle answer was `1796`.

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

At this point, you should [return to your Advent calendar](/2024) and
try another puzzle.

If you still want to see it, you can [get your puzzle
input](4/input).