diff --git a/AdventOfCode/AdventOfCode.csproj b/AdventOfCode/AdventOfCode.csproj
index 8beeaf6..9859b5e 100644
--- a/AdventOfCode/AdventOfCode.csproj
+++ b/AdventOfCode/AdventOfCode.csproj
@@ -57,6 +57,9 @@
 	<None Remove="problems\aoc2023\day7\sara.txt" />
 	<None Remove="problems\aoc2023\day8\input.txt" />
 	<None Remove="problems\aoc2023\day8\sample.txt" />
+	<None Remove="problems\aoc2023\day9\input.txt" />
+	<None Remove="problems\aoc2023\day9\sample.txt" />
+	<None Remove="problems\aoc2023\day9\sara.txt" />
   </ItemGroup>
 
 
diff --git a/AdventOfCode/Problems/AOC2023/Day9/MirageMaintenance.cs b/AdventOfCode/Problems/AOC2023/Day9/MirageMaintenance.cs
new file mode 100644
index 0000000..07af868
--- /dev/null
+++ b/AdventOfCode/Problems/AOC2023/Day9/MirageMaintenance.cs
@@ -0,0 +1,87 @@
+using AdventOfCode.Runner.Attributes;
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace AdventOfCode.Problems.AOC2023.Day9;
+[ProblemInfo(2023, 9, "Mirage Maintenance")]
+internal class MirageMaintenance : Problem<long, long>
+{
+	private long[][] _history = [];
+
+	public override void LoadInput()
+	{
+		_history = ReadInputLines("input.txt").Select(ln => ln.Split(' ').Select(long.Parse).ToArray()).ToArray();
+	}
+
+	public long CalculateNumber(long[] values, bool last = true) 
+	{ 
+		var diffs = new long[values.Length - 1];
+		for (int i = 0; i < values.Length - 1; i++)
+			diffs[i] = values[i + 1] - values[i];
+
+		if (diffs.Any(d => d != 0))
+			return last ? (values.Last() + CalculateNumber(diffs, last)) : (values.First() - CalculateNumber(diffs, last));
+		else
+			return last ? values.Last() : values.First();
+	}
+
+	[Obsolete("Optimize too soon garbage")]
+	public long GetNextNumber(long[] history)
+	{
+		var data = new List<List<long>>
+		{
+			new(history.Reverse())
+		};
+		CalculateLayer(data, 1, 1);
+		var sum = data.Select(d => d.First()).Sum();
+		Console.WriteLine();
+		Console.WriteLine(string.Join(',', history));
+		Console.WriteLine();
+
+		foreach (var item in data)
+		{
+			Console.WriteLine(string.Join(" | ", item.Select(n => n.ToString())));
+		}
+		return sum;
+	}
+
+	[Obsolete("Optimize too soon garbage")]
+	public void CalculateLayer(List<List<long>> data, int layer, int pos)
+	{
+		while (data.Count <= layer)
+			data.Add([]);
+		var lastLayer = layer - 1;
+		if (layer != 0 && data[lastLayer].Count <= pos)
+			CalculateLayer(data, lastLayer, pos + 1);
+
+		var right = data[lastLayer][pos - 1];
+		var left = data[lastLayer][pos];
+		var diff = right - left;
+		data[layer].Add(diff);
+		if (diff != 0 && pos == 1)
+			CalculateLayer(data, layer + 1, 1);
+	}
+
+	public enum State
+	{
+		Diff,
+		Expand,
+		Predict
+	}
+
+	public override void CalculatePart1()
+	{
+		//GetNextNumber(_history[2]);
+		Part1 = _history.Select(c => CalculateNumber(c)).Sum();
+	}
+
+	public override void CalculatePart2()
+	{
+		Part2 = _history.Select(c => CalculateNumber(c, false)).Sum();
+	}
+
+}