diff --git a/04/main.rs b/04/main.rs
new file mode 100644
index 0000000..0614242
--- /dev/null
+++ b/04/main.rs
@@ -0,0 +1,81 @@
+#![allow(dead_code)]
+use std::fs::File;
+use std::io;
+use std::io::BufRead;
+use std::path::Path;
+use std::time::Instant;
+
+fn main() {
+    let now = Instant::now();
+    part_one();
+    let part_one_duration = now.elapsed();
+    part_two();
+    let part_two_duration = now.elapsed();
+    println!(
+        "p1: {}ms, p2: {}ms",
+        part_one_duration.as_millis(),
+        (part_two_duration - part_one_duration).as_millis()
+    );
+}
+
+fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
+where
+    P: AsRef<Path>,
+{
+    // note that this discards a final newline
+    let file = File::open(filename)?;
+    Ok(io::BufReader::new(file).lines())
+}
+
+fn part_one() {
+    if let Ok(lines) = read_lines("./inputs/input") {
+        let mut overlaps = 0;
+        for line in lines {
+            if let Ok(ranges) = line {
+                let v: Vec<Vec<i32>> = ranges
+                    .split(",")
+                    .map(|r| r.split("-").map(|i| i.parse::<i32>().unwrap()).collect())
+                    .collect();
+                // 00 ... 01
+                // 10 ... 11
+                if (v.get(0).unwrap().get(0) <= v.get(1).unwrap().get(0)
+                    && v.get(0).unwrap().get(1) >= v.get(1).unwrap().get(1))
+                    || (v.get(1).unwrap().get(0) <= v.get(0).unwrap().get(0)
+                        && v.get(1).unwrap().get(1) >= v.get(0).unwrap().get(1))
+                {
+                    overlaps += 1;
+                }
+            }
+        }
+        println!("{}", overlaps);
+    }
+}
+
+fn part_two() {
+    if let Ok(lines) = read_lines("./inputs/input") {
+        let mut overlaps = 0;
+        for line in lines {
+            if let Ok(ranges) = line {
+                let v: Vec<Vec<i32>> = ranges
+                    .split(",")
+                    .map(|r| r.split("-").map(|i| i.parse::<i32>().unwrap()).collect())
+                    .collect();
+                // 00 ... 01
+                // 10 ... 11
+                // uuuuuugh
+                if (v.get(0).unwrap().get(0) <= v.get(1).unwrap().get(0)
+                    && v.get(0).unwrap().get(1) >= v.get(1).unwrap().get(1))
+                    || (v.get(1).unwrap().get(0) <= v.get(0).unwrap().get(0)
+                        && v.get(1).unwrap().get(1) >= v.get(0).unwrap().get(1))
+                    || (v.get(0).unwrap().get(0) <= v.get(1).unwrap().get(1)
+                        && v.get(0).unwrap().get(0) >= v.get(1).unwrap().get(0))
+                    || (v.get(0).unwrap().get(1) >= v.get(1).unwrap().get(0)
+                        && v.get(0).unwrap().get(1) <= v.get(1).unwrap().get(1))
+                {
+                    overlaps += 1;
+                }
+            }
+        }
+        println!("{}", overlaps);
+    }
+}