diff --git a/Cargo.toml b/Cargo.toml
index 869f72f..1bba829 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,5 +4,8 @@ version = "0.1.0"
 edition = "2021"
 license = "MIT"
 
+[profile.release]
+lto = true
+
 [dependencies]
 color-eyre = "0.6"
diff --git a/src/bin/day03.rs b/src/bin/day03.rs
new file mode 100644
index 0000000..e8b7785
--- /dev/null
+++ b/src/bin/day03.rs
@@ -0,0 +1,69 @@
+use color_eyre::{
+    eyre::{bail, ensure},
+    Result,
+};
+use std::io::stdin;
+
+fn part1(
+    matrix: &[u8],
+    cols: usize,
+) -> Result<impl Iterator<Item = Result<u64, std::num::ParseIntError>> + '_> {
+    let cols_sig = isize::try_from(cols)?;
+
+    Ok(matrix
+        .chunks(cols)
+        .flat_map(|chunk| chunk.split(|pred| !(*pred as char).is_ascii_digit()))
+        .filter(|s| !s.is_empty())
+        .map(move |slice| {
+            let ix = slice.as_ptr() as usize - matrix.as_ptr() as usize;
+            (ix..slice.len() + ix)
+                .flat_map(|ix| {
+                    (ix % cols != 0)
+                        .then_some([-1, cols_sig - 1, -cols_sig - 1])
+                        .into_iter()
+                        .chain((ix % cols != cols - 1).then_some([1, cols_sig + 1, -cols_sig + 1]))
+                        .flatten()
+                        .chain([-cols_sig, cols_sig])
+                        .flat_map(move |offset| ix.checked_add_signed(offset))
+                })
+                .flat_map(|ix| matrix.get(ix))
+                .any(|&b| (b as char).is_ascii_punctuation() && b != b'.')
+                .then(|| String::from_utf8_lossy(slice).parse::<u64>())
+                .transpose()
+                .map(|x| x.unwrap_or_default())
+        }))
+}
+
+fn part2(matrix: &[u8], cols: usize) -> Result<impl Iterator<Item = Result<u64>> + '_> {
+    
+    Ok(std::iter::once(Ok(0)))
+}
+
+fn main() -> Result<()> {
+    let mut lines = stdin().lines();
+    let line = match lines.next() {
+        Some(Ok(line)) => line,
+        Some(Err(e)) => bail!(e),
+        None => {
+            println!("0");
+            return Ok(());
+        }
+    };
+
+    let cols = line.len();
+    let mut matrix = line.as_bytes().to_owned();
+
+    lines.try_for_each(|ln| {
+        let ln = ln?;
+        ensure!(ln.len() == cols, "Invalid column count");
+        matrix.extend_from_slice(ln.as_bytes());
+        Ok(())
+    })?;
+
+    println!(
+        "{}",
+        part1(&matrix, cols)?.try_fold::<_, _, Result<_>>(0, |acc, x| Ok(acc + x?))?
+    );
+
+    Ok(())
+}