diff --git a/advent-of-code/Program.fs b/advent-of-code/Program.fs
index e8cb781..86f8446 100644
--- a/advent-of-code/Program.fs
+++ b/advent-of-code/Program.fs
@@ -4,36 +4,40 @@ open advent_of_code.tasks
 
 [<EntryPoint>]
 let main _ =
-    let _, day1Star1 = day_1.Star1.main 50 0
-    printfn $"{day1Star1}"
-    let _, day1Star2 = day_1.Star2.main 50 0
-    printfn $"{day1Star2}"
-    let day2Star1 = day_2.Star1.main
-    printfn $"{day2Star1}"
-    let day2Star2 = day_2.Star2.main
-    printfn $"{day2Star2}"
-    let day3Star1 = day_3.Star1.main
-    printfn $"{day3Star1}"
-    let day3Star2 = day_3.Star2.main
-    printfn $"{day3Star2}"
-    let day4Star1 = day_4.Star1.main
-    printfn $"{day4Star1}"
-    let day4Star2 = day_4.Star2.main
-    printfn $"{day4Star2}"
-    let day5Star1 = day_5.Star1.main
-    printfn $"%A{day5Star1}"
-    let day5Star2 = day_5.Star2.main
-    printfn $"%A{day5Star2}"
-    let day6Star1 = day_6.Star1.main
-    printfn $"%A{day6Star1}"
-    let day6Star2 = day_6.Star2.main
-    printfn $"%A{day6Star2}"
-    let day7Star1 = day_7.Star1.main
-    printfn $"%A{day7Star1}"
-    let day7Star2 = day_7.Star2.main
-    printfn $"%A{day7Star2}"
-    let day8Star1 = day_8.Star1.main
-    printfn $"%A{day8Star1}"
-    let day8Star2 = day_8.Star2.main
-    printfn $"%A{day8Star2}"
+    // let _, day1Star1 = day_1.Star1.main 50 0
+    // printfn $"{day1Star1}"
+    // let _, day1Star2 = day_1.Star2.main 50 0
+    // printfn $"{day1Star2}"
+    // let day2Star1 = day_2.Star1.main
+    // printfn $"{day2Star1}"
+    // let day2Star2 = day_2.Star2.main
+    // printfn $"{day2Star2}"
+    // let day3Star1 = day_3.Star1.main
+    // printfn $"{day3Star1}"
+    // let day3Star2 = day_3.Star2.main
+    // printfn $"{day3Star2}"
+    // let day4Star1 = day_4.Star1.main
+    // printfn $"{day4Star1}"
+    // let day4Star2 = day_4.Star2.main
+    // printfn $"{day4Star2}"
+    // let day5Star1 = day_5.Star1.main
+    // printfn $"%A{day5Star1}"
+    // let day5Star2 = day_5.Star2.main
+    // printfn $"%A{day5Star2}"
+    // let day6Star1 = day_6.Star1.main
+    // printfn $"%A{day6Star1}"
+    // let day6Star2 = day_6.Star2.main
+    // printfn $"%A{day6Star2}"
+    // let day7Star1 = day_7.Star1.main
+    // printfn $"%A{day7Star1}"
+    // let day7Star2 = day_7.Star2.main
+    // printfn $"%A{day7Star2}"
+    // let day8Star1 = day_8.Star1.main
+    // printfn $"%A{day8Star1}"
+    // let day8Star2 = day_8.Star2.main
+    // printfn $"%A{day8Star2}"
+    let day9Star1 = day_9.Star1.main
+    printfn $"%A{day9Star1}"
+    let day9Star2 = day_9.Star2.main
+    printfn $"%A{day9Star2}"
     0
diff --git a/advent-of-code/tasks/day-9/Star1.fs b/advent-of-code/tasks/day-9/Star1.fs
new file mode 100644
index 0000000..974d694
--- /dev/null
+++ b/advent-of-code/tasks/day-9/Star1.fs
@@ -0,0 +1,35 @@
+module advent_of_code.tasks.day_9.Star1
+
+open System
+open System.IO
+
+let stream = new StreamReader("tasks/day-9/input.txt")
+
+type Point2D =
+    struct
+        val X: int64
+        val Y: int64
+        new(s: string) =
+            let splitS = s.Split(',') |> Array.map int64
+            let x, y = splitS[0], splitS[1]
+            {
+                X = x
+                Y = y
+            }
+            
+        override this.ToString() =
+            $"Point2D with x = {this.X} y = {this.Y}"
+    end
+
+let getRect(p: Point2D * Point2D) =
+    let p1, p2 = p.Deconstruct()
+    abs (p1.X - p2.X + (1 |> int64)) * abs (p1.Y - p2.Y + (1 |> int64))
+
+let notSame (p: Point2D * Point2D) =
+    let p1, p2 = p.Deconstruct()
+    p1.X <> p2.X && p1.Y <> p2.Y
+
+let main =
+    let points = stream.ReadToEnd().Split('\n') |> Array.map Point2D
+    let allRects = (Array.allPairs points points) |> Array.filter notSame |> Array.map getRect
+    allRects |> Array.max
diff --git a/advent-of-code/tasks/day-9/Star2.fs b/advent-of-code/tasks/day-9/Star2.fs
new file mode 100644
index 0000000..070ad62
--- /dev/null
+++ b/advent-of-code/tasks/day-9/Star2.fs
@@ -0,0 +1,56 @@
+module advent_of_code.tasks.day_9.Star2
+
+// UNFINISHED. Submission was found manually.
+
+open System
+open System.IO
+
+let stream = new StreamReader("tasks/day-9/input.txt")
+
+type Point2D =
+    struct
+        val X: int64
+        val Y: int64
+        new(s: string) =
+            let splitS = s.Split(',') |> Array.Parallel.map int64
+            let x, y = splitS[0], splitS[1]
+            {
+                X = x
+                Y = y
+            }
+        
+        new(x: int64, y: int64) =
+            {
+                X = x
+                Y = y
+            }
+            
+        override this.ToString() =
+            $"Point2D with x = {this.X} y = {this.Y}"
+    end
+
+let getRect(p: Point2D * Point2D) =
+    let p1, p2 = p.Deconstruct()
+    abs (p1.X - p2.X + (1 |> int64)) * abs (p1.Y - p2.Y + (1 |> int64))
+
+let notSame (p: Point2D * Point2D) =
+    let p1, p2 = p.Deconstruct()
+    p1.X <> p2.X && p1.Y <> p2.Y
+
+let linesIntersect (l1: Point2D * Point2D) (l2: Point2D * Point2D) =
+    let (p1, p2) = l1.Deconstruct()
+    let (q1, q2) = l2.Deconstruct()
+    if q1.X = q2.X then
+        q1.X > min p1.X p2.X && q1.X < max p1.X p2.X && min q1.Y q2.Y < max p1.Y p2.Y && max q1.Y q2.Y > min p1.Y p2.Y
+    else
+        max q1.X q2.X > min p1.X p2.X && min q1.X q2.X < max p1.X p2.X && q1.Y < max p1.Y p2.Y && q1.Y > min p1.Y p2.Y
+
+let isInPoly (polygon: Point2D list) (p: Point2D * Point2D) =
+    let edges = List.pairwise polygon @ [List.last polygon, List.head polygon] |> Array.ofList
+    edges |> Array.Parallel.forall (linesIntersect p >> not)
+
+let main =
+    let points = stream.ReadToEnd().Split('\n') |> Array.Parallel.map Point2D
+    let pointList = points |> List.ofArray
+    let allRects = (Array.allPairs points points) |> Array.Parallel.filter notSame |> Array.Parallel.filter (isInPoly pointList)
+    allRects |> Array.Parallel.maxBy getRect |> getRect