diff --git a/src/bin/day04.rs b/src/bin/day04.rs
index d91b2a9..884d67c 100644
--- a/src/bin/day04.rs
+++ b/src/bin/day04.rs
@@ -4,7 +4,6 @@ use std::fs;
 use std::collections::HashSet;
 
 use anyhow::{Context, Result};
-use regex::Regex;
 
 fn main() -> Result<()> {
     let filename = env::args()
@@ -12,50 +11,33 @@ fn main() -> Result<()> {
         .context("./day04 <path to puzzle input>")?;
     let input = fs::read_to_string(filename)?;
 
-    let re = Regex::new(r"\d+")?;
-
     let lines = input.lines().collect::<Vec<_>>();
 
     let mut count: Vec<usize> = vec![1; lines.len()];
 
     let mut part1 = 0;
     for (line_num, line) in lines.into_iter().enumerate() {
-        let mut hs = HashSet::new();
-
         let (_, card_text) = line.split_once(':').unwrap();
-        let (winning, mine) = card_text.split_once('|').unwrap();
+        let (winning_str, mine_str) = card_text.split_once('|').unwrap();
 
-        let winning_nums = re
-            .find_iter(winning)
-            .map(|m| m.as_str().parse::<u32>().unwrap());
+        let winning = winning_str
+            .split_ascii_whitespace()
+            .map(|m| m.parse::<i32>().unwrap())
+            .collect::<HashSet<_>>();
 
-        let my_nums = re
-            .find_iter(mine)
-            .map(|m| m.as_str().parse::<u32>().unwrap());
+        let mine = mine_str
+            .split_ascii_whitespace()
+            .map(|m| m.parse::<i32>().unwrap());
 
-        for i in winning_nums {
-            hs.insert(i);
-        }
-
-        let mut num_matches: usize = 0;
-
-        for i in my_nums {
-            if hs.contains(&i) {
-                num_matches += 1;
-            }
-        }
-
-        for i in line_num + 1..line_num + num_matches + 1 {
-            if i >= count.len() {
-                break;
-            }
+        let num_matches = mine.filter(|n| winning.contains(n)).count();
 
+        for i in (line_num + 1)..(line_num + num_matches + 1).min(count.len()) {
             count[i] += count[line_num];
         }
 
-		if num_matches > 0 {
-			part1 += 1 << (num_matches - 1);
-		}
+        if num_matches > 0 {
+            part1 += 1 << (num_matches - 1);
+        }
     }
 
     let part2 = count.into_iter().sum::<usize>();