using System.Collections.Generic;

public class Program

{

    const float allowedGroupDeviation = 2;

​

    static List<List<float[]>> SortAndGroup(List<float[]> data, int key)

    {

        List<float[]> sorted = data;

        sorted.Sort((l, r) => l[key].CompareTo(r[key]));

​

        List<List<float[]>> groups = new List<List<float[]>>();

        groups.Add(new List<float[]>() { sorted[0] });

​

        for (int i = 1; i < sorted.Count; i++)

        {

            float[] item = sorted[i];

            List<float[]> currentSet = groups[groups.Count - 1];

            float[] currentLowestInSet = currentSet[0];

​

            if (item[key] - currentLowestInSet[key] < allowedGroupDeviation)

            {

                currentSet.Add(item);

            }

            else

            {

                groups.Add(new List<float[]>() { item });

            }

        }

​

        return groups;

    }

    public static void Main()

    {

        // Readfile here

        string data = "35.13,43.412,12.92\n18.51,36.708,14.99";

        string[] lines = data.Replace("\r", "").Split();

​

        List<float[]> dataSet = new List<float[]>();

        for (int i = 0; i < lines.Length; i++)

        {

            string[] splitStrs = lines[i].Split(',');

            float[] nums = new float[] {

                float.Parse(splitStrs[0]),

                float.Parse(splitStrs[1]),

                float.Parse(splitStrs[2]),

            };

            dataSet.Add(nums);

        }

​

        List<List<float[]>> finalGroups = new List<List<float[]>>();

​

        List<List<float[]>> xGroups = SortAndGroup(dataSet, 0);

        foreach (List<float[]> xGroup in xGroups)

        {

            List<List<float[]>> yGroups = SortAndGroup(xGroup, 1);

            foreach (List<float[]> yGroup in yGroups)

            {

                List<List<float[]>> zGroups = SortAndGroup(yGroup, 2);

                foreach (List<float[]> group in zGroups)

                {

                    finalGroups.Add(group);

                }

            }

        }

​

        string output = "";

​

        for (int i = 0; i < finalGroups.Count; i++)

        {

            output += "Group " + (i + 1) + ",,\n";

            foreach (float[] item in finalGroups[i])

            {

                output += item[0] + "," + item[1] + "," + item[2] + "\n";

            }

            output += ",,\n,,\n";

        }

​

        System.Console.Write(output);

​

        // Write file here

    }

}