diff --git a/Cargo.lock b/Cargo.lock
index 2056020..8e4b96e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -11,6 +11,7 @@ name = "aoc_2018"
 version = "0.1.0"
 dependencies = [
  "chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "gcd 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.7.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -35,6 +36,11 @@ name = "either"
 version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "gcd"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "itertools"
 version = "0.7.11"
@@ -158,6 +164,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "082bb9b28e00d3c9d39cc03e64ce4cea0f1bb9b3fde493f0cbc008472d22bdf4"
 "checksum chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "45912881121cb26fad7c38c17ba7daa18764771836b34fab7d3fbd93ed633878"
 "checksum either 1.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3be565ca5c557d7f59e7cfcf1844f9e3033650c929c6566f511e8005f205c1d0"
+"checksum gcd 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0896cb73353671dbe2b17312c97b55b7032831d28c809c703bece4a392b1df3a"
 "checksum itertools 0.7.11 (registry+https://github.com/rust-lang/crates.io-index)" = "0d47946d458e94a1b7bcabbf6521ea7c037062c81f534615abcad76e84d4970d"
 "checksum lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "a374c89b9db55895453a74c1e38861d9deec0b01b405a82516e9d5de4820dea1"
 "checksum libc 0.2.44 (registry+https://github.com/rust-lang/crates.io-index)" = "10923947f84a519a45c8fefb7dd1b3e8c08747993381adee176d7a82b4195311"
diff --git a/Cargo.toml b/Cargo.toml
index b3fd792..8630dad 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,3 +8,4 @@ edition = "2018"
 regex = "1.1.0"
 chrono = "0.4.6"
 itertools = "0.7.11"
+gcd = "1.1.0"
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 44c35ec..fc32bc4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,4 +1,4 @@
 fn main() {
-    aoc_2018::tasks::day23::task1();
-    // aoc_2018::tasks::day15::task2();
+    // aoc_2018::tasks::day23::task1();
+    aoc_2018::tasks::day23::task2();
 }
diff --git a/src/tasks/day23.rs b/src/tasks/day23.rs
index a57205c..5626516 100644
--- a/src/tasks/day23.rs
+++ b/src/tasks/day23.rs
@@ -30,6 +30,70 @@ pub fn task1() {
     println!("There are {} bots in range of the big bot.", bots_in_range);
 }
 
+pub fn task2() {
+    let input = utils::read_file("input/day23.txt");
+    let regex =
+        Regex::new(r"^pos=<(?P<x>-?\d+),(?P<y>-?\d+),(?P<z>-?\d+)>, r=(?P<range>\d+)$").unwrap();
+    let bots: Vec<Bot> = input
+        .lines()
+        .map(|line| {
+            let m = regex.captures(line).unwrap();
+            let x = m["x"].parse::<isize>().unwrap();
+            let y = m["y"].parse::<isize>().unwrap();
+            let z = m["z"].parse::<isize>().unwrap();
+            let range = m["range"].parse::<usize>().unwrap();
+
+            Bot { x, y, z, range }
+        })
+        .collect();
+
+    // let r_min = bots.iter().min_by_key(|it| it.range).unwrap().range;
+    // let r_max = bots.iter().max_by_key(|it| it.range).unwrap().range;
+    // println!("Radius min max: {}/{}", r_min, r_max);
+    // let x_min = bots.iter().min_by_key(|it| it.x).unwrap().x;
+    // let x_max = bots.iter().max_by_key(|it| it.x).unwrap().x;
+    // println!("X range: {}", x_max - x_min);
+    // let y_min = bots.iter().min_by_key(|it| it.y).unwrap().y;
+    // let y_max = bots.iter().max_by_key(|it| it.y).unwrap().y;
+    // println!("Y range: {}", y_max - y_min);
+    // let z_min = bots.iter().min_by_key(|it| it.z).unwrap().z;
+    // let z_max = bots.iter().max_by_key(|it| it.z).unwrap().z;
+    // println!("Z range: {}", z_max - z_min);
+
+    let neighbor_counts: Vec<(Bot, usize)> = bots
+        .iter()
+        .flat_map(|bot| bot.corners())
+        .map(|corner| {
+            let count = bots
+                .iter()
+                .filter(|bot| bot.distance(&corner) <= bot.range)
+                .count();
+            (corner, count)
+        })
+        .collect();
+
+    let max = neighbor_counts.iter().max_by_key(|it| it.1).unwrap().1;
+
+    let start = Bot {
+        x: 0,
+        y: 0,
+        z: 0,
+        range: 0,
+    };
+    let candidates = neighbor_counts.iter().filter(|it| it.1 == max).count();
+    println!("{} points in range of {} bots", candidates, max);
+    let candidate = neighbor_counts
+        .iter()
+        .filter(|it| it.1 == max)
+        .min_by_key(|it| it.0.distance(&start));
+
+    println!(
+        "Corner with most bots in range: {:?}",
+        candidate.unwrap().0.distance(&start)
+    );
+    // wrong: 37446460,43177892,57318660; 137943012; 102224079;
+}
+
 #[derive(Debug)]
 struct Bot {
     x: isize,
@@ -42,4 +106,45 @@ impl Bot {
     fn distance(&self, other: &Self) -> usize {
         ((other.x - self.x).abs() + (other.y - self.y).abs() + (other.z - self.z).abs()) as usize
     }
+
+    fn corners(&self) -> Vec<Self> {
+        vec![
+            Bot {
+                x: self.x + self.range as isize,
+                y: self.y,
+                z: self.z,
+                range: 0,
+            },
+            Bot {
+                x: self.x - self.range as isize,
+                y: self.y,
+                z: self.z,
+                range: 0,
+            },
+            Bot {
+                x: self.x,
+                y: self.y + self.range as isize,
+                z: self.z,
+                range: 0,
+            },
+            Bot {
+                x: self.x,
+                y: self.y - self.range as isize,
+                z: self.z,
+                range: 0,
+            },
+            Bot {
+                x: self.x,
+                y: self.y,
+                z: self.z + self.range as isize,
+                range: 0,
+            },
+            Bot {
+                x: self.x,
+                y: self.y,
+                z: self.z - self.range as isize,
+                range: 0,
+            },
+        ]
+    }
 }