C#-Code

    class Program
    {
        static void Main(string[] args)
        {
            ZahlenBox box = new ZahlenBox(6,3,4);
            Console.WriteLine(box);
            int lowest = box.find((x, y) => x < y);
            Console.WriteLine(lowest);
            Console.WriteLine(String.Join("\n", box.whereAre(lowest)));
            Console.ReadKey();
        }
    }

    class ZahlenBox
    {
        private int[,,] matrix;

        public ZahlenBox(int p1, int p2, int p3)
        {
            Random zufall = new Random();
            matrix = new int[p1, p2, p3];
            for (int x = 0; x < matrix.GetLength(0); x++ )
            {
                for (int y = 0; y < matrix.GetLength(1); y++)
                {
                    for (int z = 0; z < matrix.GetLength(2); z++)
                    {
                        matrix[x, y, z] = zufall.Next(100);
                    }
                }
            }
        }

        internal int find(Func<int,int,bool> Comperator)
        {
            int? save = null;
            foreach (var cell in matrix)
            {
                if (save == null) save = cell; else if (Comperator( cell,(int)save)) save = cell;                
            }
            return (int)save;
        }

        public override string ToString()
        {
            string res = "[";
            for (int x = 0; x < matrix.GetLength(0); x++)
            {
                res = res + "{";
                for (int y = 0; y < matrix.GetLength(1); y++)
                {
                    res = res + "(";
                    for (int z = 0; z < matrix.GetLength(2); z++)
                    {
                        res = res + matrix[x, y, z].ToString("00") + ", ";
                    }
                    res = res.Substring(0, res.Length - 2);
                    res = res + "), ";
                }
                res = res.Substring(0, res.Length - 2);
                res = res + "},\n ";
            }
            res = res.Substring(0, res.Length - 3);
            res = res + "]";
            return res;
        }

        internal string[] whereAre(int entry)
        {
            List<string> resL = new List<string>();
            for (int x = 0; x < matrix.GetLength(0); x++)
            {
                for (int y = 0; y < matrix.GetLength(1); y++)
                {
                    for (int z = 0; z < matrix.GetLength(2); z++)
                    {
                        if (matrix[x, y, z] == entry) resL.Add("Zeile: " + x + " Gruppe: " + y + " Element: " + z);
                    }
                }
            }
            return resL.ToArray();
        }
    }