diff --git a/2024/04/p1/main.rs b/2024/04/p1/main.rs
new file mode 100644
index 0000000..71c9eef
--- /dev/null
+++ b/2024/04/p1/main.rs
@@ -0,0 +1,112 @@
+use std::{fs::File, io::Read};
+
+fn main() -> std::io::Result<()> {
+    let args: Vec<_> = std::env::args().collect();
+    let filename = &args[1];
+
+    let mut contents = String::new();
+    let mut file = File::open(filename)?;
+    file.read_to_string(&mut contents)?;
+
+    let lines: Vec<_> = contents.lines().collect();
+    // let height = lines.len();
+    // let width = lines[0].len();
+    // let res_buf: Vec<Vec<_>> = (0..height)
+    //     .map(|_| (0..width).map(|_| '.').collect())
+    //     .collect();
+    // _ = &res_buf;
+
+    print_res(
+        &lines
+            .iter()
+            .map(|ln| ln.chars().collect::<Vec<_>>())
+            .collect::<Vec<_>>(),
+    );
+
+    // let r = eq_in_dir(
+    //     &lines
+    //         .iter()
+    //         .map(|ln| ln.chars().collect::<Vec<_>>())
+    //         .collect::<Vec<_>>(),
+    //     (4, 0),
+    //     (1, 1),
+    //     "MAS".chars(),
+    // );
+    // println!("{r:?}");
+    // return Ok(());
+
+    let mut t = 0;
+    for (i, ln) in lines.iter().enumerate() {
+        for (j, ch) in ln.chars().enumerate() {
+            if ch == 'X' {
+                // println!("X found at ({j}, {i})");
+                let map = [-1, 0, 1].map(|i| [-1, 0, 1].map(|j| (i, j)));
+                for dir in map.as_flattened() {
+                    let r = eq_in_dir(
+                        &lines
+                            .iter()
+                            .map(|ln| ln.chars().collect::<Vec<_>>())
+                            .collect::<Vec<_>>(),
+                        (j, i),
+                        *dir,
+                        "MAS".chars(),
+                    );
+                    if r { t += 1; }
+                    // println!(" {dir:?}: {r:?}");
+                }
+            }
+        }
+    }
+
+    println!("total {t}");
+    Ok(())
+}
+
+fn eq_in_dir(
+    buf: &[Vec<char>],
+    pos: (usize, usize),
+    dir: (isize, isize),
+    matches: impl Iterator<Item = char>,
+) -> bool {
+    opt_eq_in_dir(buf, pos, dir, matches).is_some()
+}
+
+fn opt_eq_in_dir(
+    buf: &[Vec<char>],
+    pos: (usize, usize),
+    dir: (isize, isize),
+    mut matches: impl Iterator<Item = char>,
+) -> Option<()> {
+
+    // println!(" {pos:?} {dir:?}");
+    let Some(must_match) = matches.next() else {
+        return Some(());
+    };
+    // println!("  {must_match:?}");
+
+    let new_1 = do_the_thing(dir.1, pos.1)?;
+    let new_0 = do_the_thing(dir.0, pos.0)?;
+    let ln = buf.get(new_1)?;
+    let ch = ln.get(new_0)?;
+    // println!("   {ch:?}");
+
+    if must_match == *ch {
+        opt_eq_in_dir(buf, (new_0, new_1), dir, matches)
+    } else {
+        None
+    }
+}
+
+fn do_the_thing(a: isize, b: usize) -> Option<usize> {
+    let r = b as isize + a;
+    if r < 0 {
+        return None;
+    }
+    Some(r as usize)
+}
+
+fn print_res(buf: &[Vec<char>]) {
+    for ln in buf.iter() {
+        println!("{}", ln.iter().collect::<String>())
+    }
+}
diff --git a/README.md b/README.md
index 3cbb8aa..ab888dc 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,7 @@ What is AOC??: [adventofcode](https://adventofcode.com)
 
 All this is a mix of langs, but in general:
 * `asm`: I use nasm, at least for now for assembly programs (linux, x86\_64), no special linking normallly, so just elf64 compile and link.
-* `zig`: No need to set up a full project, simply `zig build-exe -fstrip -OReleaseFast main.zig`
+* `zig`: No need to set up a full project, simply `zig build-exe -O ReleaseFast -fsingle-threaded -fno-unwind-tables -fno-error-tracing -fno-formatted-panics -fstrip -fno-stack-protector main.zig` for max performance.
+* `rust`: No need for projects neither, also `rustc -Copt-level=3 -Ctarget-cpu=native -Cpanic=abort -Cstrip=symbols -Coverflow_checks=n -Clto=fat` for squeezing performance.
 
 I also tend to use `perf stat` to check their performance.