diff --git a/src/bin/day04.rs b/src/bin/day04.rs
index 4910c16..6bd8ddb 100644
--- a/src/bin/day04.rs
+++ b/src/bin/day04.rs
@@ -1,6 +1,5 @@
-use std::ops::{Range, RangeInclusive};
+use std::ops::RangeInclusive;
 use std::str::FromStr;
-use std::{collections::HashSet, ops::RangeBounds};
 
 use aoc_2022::*;
 
@@ -33,29 +32,31 @@ impl FromStr for Assignment {
     }
 }
 
+impl Assignment {
+    fn fully_overlap(&self) -> bool {
+        let Assignment(l, r) = self;
+
+        (l.start() <= r.start() && r.end() <= l.end())
+            || (r.start() <= l.start() && l.end() <= r.end())
+    }
+
+    fn overlap(&self) -> bool {
+        let Assignment(l, r) = self;
+
+        (l.contains(r.start()) || l.contains(r.end()))
+            || (r.contains(l.start()) || r.contains(l.end()))
+    }
+}
+
 type Input = Vec<Assignment>;
-type Output = i32;
+type Output = usize;
 
 fn part_1(input: &Input) -> Output {
-    input
-        .iter()
-        .filter(|Assignment(l, r)| {
-            (l.start() <= r.start() && r.end() <= l.end())
-                || (r.start() <= l.start() && l.end() <= r.end())
-        })
-        .count() as i32
+    input.iter().filter(|a| a.fully_overlap()).count()
 }
 
 fn part_2(input: &Input) -> Output {
-    input
-        .iter()
-        .filter(|Assignment(l, r)| {
-            l.contains(r.start())
-                || l.contains(r.end())
-                || r.contains(l.start())
-                || r.contains(l.end())
-        })
-        .count() as i32
+    input.iter().filter(|a| a.overlap()).count()
 }
 
 fn parse_input(pathname: &str) -> Input {