diff --git a/d4/Cargo.lock b/d4/Cargo.lock
new file mode 100644
index 0000000..35783ca
--- /dev/null
+++ b/d4/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "d4"
+version = "0.1.0"
diff --git a/d4/Cargo.toml b/d4/Cargo.toml
new file mode 100644
index 0000000..d057ef5
--- /dev/null
+++ b/d4/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "d4"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/d4/src/main.rs b/d4/src/main.rs
new file mode 100644
index 0000000..e4259e9
--- /dev/null
+++ b/d4/src/main.rs
@@ -0,0 +1,59 @@
+use std::{fs::read_to_string, io::Result};
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+struct Range {
+    start: u32,
+    end: u32,
+}
+
+impl Range {
+    pub fn from_str(s: &str) -> Self {
+        let mut parts = s.split("-");
+        let start = parts.next().unwrap().parse().unwrap();
+        let end = parts.next().unwrap().parse().unwrap();
+        Self { start, end }
+    }
+
+    pub fn includes(self, other: Self) -> bool {
+        self.start <= other.start && self.end >= other.end
+    }
+
+    pub fn overlaps(self, other: Self) -> bool {
+        (self.start <= other.start && other.start <= self.end)
+            || (other.start <= self.start && self.start <= other.end)
+            || (self.end <= other.end && other.end <= self.end)
+            || (other.end <= self.end && self.end <= other.end)
+    }
+}
+
+fn main() -> Result<()> {
+    let mut result_p1 = 0;
+    let mut result_p2 = 0;
+
+    for line in read_to_string("input.txt")?.split("\n") {
+        if line.is_empty() {
+            continue;
+        }
+
+        let (left, right) = {
+            let mut parts = line.split(",");
+            let left = parts.next();
+            (left.unwrap(), parts.next().unwrap())
+        };
+
+        let left = Range::from_str(left);
+        let right = Range::from_str(right);
+
+        if left.includes(right) || right.includes(left) {
+            result_p1 += 1;
+        }
+        if left.overlaps(right) {
+            result_p2 += 1;
+        }
+    }
+
+    println!("Part 1: {}", result_p1);
+    println!("Part 2: {}", result_p2);
+
+    Ok(())
+}