static string CalculateCheapestMonth(ListNodes<Residents> residentsListNodes, ListNodes<Utilities> utilitiesListNodes)
        {
            var cheapestMonth = new Dictionary<string, Dictionary<string, double>>();
            var cheapestMonthListNodes = new ListNodes<CheapestMonth>();
            var temp = residentsListNodes;
            for (residentsListNodes.StartingNode(); residentsListNodes.Contains(); residentsListNodes.RightNode())
            {
                if (cheapestMonth.ContainsKey(residentsListNodes.GetData().Month))
                {
                    if (cheapestMonth[residentsListNodes.GetData().Month].ContainsKey(residentsListNodes.GetData().UtilityCode))
                    {

                        cheapestMonth[residentsListNodes.GetData().Month][residentsListNodes.GetData().UtilityCode] +=
                            FindUtilityPrice(utilitiesListNodes, residentsListNodes.GetData().UtilityCode) * residentsListNodes.GetData().ServiceCount;
                    }
                    else
                    {
                        cheapestMonth[residentsListNodes.GetData().Month].Add(
                       residentsListNodes.GetData().UtilityCode,
                       FindUtilityPrice(utilitiesListNodes, residentsListNodes.GetData().UtilityCode) * residentsListNodes.GetData().ServiceCount
                       );
                    }
                }
                else
                {
                    cheapestMonth.Add(residentsListNodes.GetData().Month, new Dictionary<string, double>());
                    cheapestMonth[residentsListNodes.GetData().Month].Add(
                        residentsListNodes.GetData().UtilityCode,
                        FindUtilityPrice(utilitiesListNodes, residentsListNodes.GetData().UtilityCode) * residentsListNodes.GetData().ServiceCount
                        );
                }
            }

            foreach (KeyValuePair<string, Dictionary<string, double>> item in cheapestMonth)
            {
                foreach (KeyValuePair<string, double> utility in cheapestMonth[item.Key])
                {
                    cheapestMonthListNodes.AddData(new CheapestMonth(item.Key, utility.Key, utility.Value));
                }
            }

            var cheapestMonthUtility = cheapestMonthListNodes.OrderBy(x => x.Price).FirstOrDefault();

            for (utilitiesListNodes.StartingNode(); utilitiesListNodes.Contains(); utilitiesListNodes.RightNode())
            {
                if (cheapestMonthUtility.UtilityCode == utilitiesListNodes.GetData().ServiceCode)
                {
                    cheapestMonthUtility.UtilityCode = utilitiesListNodes.GetData().ServiceName;
                }
            }
            if (cheapestMonthUtility != null)
            {
                return $"{cheapestMonthUtility.Month} mėnesį {cheapestMonthUtility.UtilityCode} kainavo pigiausiai";
            }
            return "Nerasta";
        }
        static double CalculateResidentsAverageMoneySpent(ListNodes<Residents> residentsListNodes)
        {
            var count = 0;

            for (residentsListNodes.StartingNode(); residentsListNodes.Contains(); residentsListNodes.RightNode())
            {
                count++;
            }

            return CalculateResidentsAllMoneySpent(residentsListNodes) / count;
        }
        static double CalculateResidentsAllMoneySpent(ListNodes<Residents> residentsListNodes)
        {
            var sum = 0.0;

            for (residentsListNodes.StartingNode(); residentsListNodes.Contains(); residentsListNodes.RightNode())
            {
                sum += residentsListNodes.GetData().MoneySpent;
            }

            return sum;
        }
 static void CalculateMoneySpent(ListNodes<Utilities> utilitiesListNodes, ListNodes<Residents> residentsListNodes)
 {
     for (residentsListNodes.StartingNode(); residentsListNodes.Contains(); residentsListNodes.RightNode())
     {
         for (utilitiesListNodes.StartingNode(); utilitiesListNodes.Contains(); utilitiesListNodes.RightNode())
         {
             if (residentsListNodes.GetData().UtilityCode == utilitiesListNodes.GetData().ServiceCode)
             {
                 residentsListNodes.GetData().MoneySpent = utilitiesListNodes.GetData().ServiceUnitPrice * residentsListNodes.GetData().ServiceCount;
             }
         }
     }
 }
        static double FindUtilityPrice(ListNodes<Utilities> utilitiesListNodes, string residentUtilityCode)
        {
            var utilityPrice = 0.0;
            for (utilitiesListNodes.StartingNode(); utilitiesListNodes.Contains(); utilitiesListNodes.RightNode())
            {

                if (residentUtilityCode == utilitiesListNodes.GetData().ServiceCode)
                {
                    utilityPrice = utilitiesListNodes.GetData().ServiceUnitPrice;
                    break;
                }
            }
            return utilityPrice;
        }
        static ListNodes<Residents> FilterResidentsByMoneySpent(ListNodes<Residents> residentsListNodes)
        {
            var filteredResidents = new ListNodes<Residents>();
            var averageMoneySpent = CalculateResidentsAverageMoneySpent(residentsListNodes);

            for (residentsListNodes.StartingNode(); residentsListNodes.Contains(); residentsListNodes.RightNode())
            {
                if (averageMoneySpent > residentsListNodes.GetData().MoneySpent)
                {
                    filteredResidents.AddData(residentsListNodes.GetData());
                }
            }

            return filteredResidents;
        }
        void UtilitiesTable(ListNodes<Utilities> utilitiesListNodes)
        {
            var rowTop = new TableRow();

            for (int i = 0; i < 3; i++)
            {
                var cell = new TableCell();
                cell.BorderStyle = BorderStyle.Solid;
                cell.BorderWidth = 3;
                cell.Font.Size = 15;
                cell.Height = 30;
                cell.Width = 30;

                if (i == 0) cell.Text = "Paslaugos kodas";

                if (i == 1) cell.Text = "Paslaugos pavadinimas";

                if (i == 2) cell.Text = "Paslaugos kaina vnt.";

                rowTop.Cells.Add(cell);
            }
            Table1.Rows.Add(rowTop);

            for (utilitiesListNodes.StartingNode(); utilitiesListNodes.Contains(); utilitiesListNodes.RightNode())
            {
                var row = new TableRow();

                for (int i = 0; i < 3; i++)
                {
                    var cell = new TableCell();
                    cell.BorderStyle = BorderStyle.Solid;
                    cell.BorderWidth = 3;
                    cell.Font.Size = 15;
                    cell.Height = 30;
                    cell.Width = 30;

                    if (i == 0) cell.Text = utilitiesListNodes.GetData().ServiceCode;

                    if (i == 1) cell.Text = utilitiesListNodes.GetData().ServiceName;

                    if (i == 2) cell.Text = utilitiesListNodes.GetData().ServiceUnitPrice.ToString();

                    row.Cells.Add(cell);
                }

                Table1.Rows.Add(row);
            }
        }
        static ListNodes<Residents> RemoveResidents(ListNodes<Residents> residentsList, ListNodes<Utilities> utilitiesList, string chosenMonth, string chosenUtility)
        {
            var utilityCode = "";
            var removedResidents = residentsList;

            for (utilitiesList.StartingNode(); utilitiesList.Contains(); utilitiesList.RightNode())
            {
                if (utilitiesList.GetData().ServiceName == chosenUtility)
                {
                    utilityCode = utilitiesList.GetData().ServiceCode;
                    break;
                }
            }

            var index = 0;

            for (removedResidents.StartingNode(); removedResidents.Contains(); removedResidents.RightNode())
            {
                if (removedResidents.GetData().Month != chosenMonth || removedResidents.GetData().ServiceCount <= 0 || removedResidents.GetData().UtilityCode != utilityCode)
                {
                    index++;
                }
            }

            for (int i = 0; i < index; i++)
            {
                for (removedResidents.StartingNode(); removedResidents.Contains(); removedResidents.RightNode())
                {
                    if (removedResidents.GetData().Month != chosenMonth || removedResidents.GetData().ServiceCount <= 0 || removedResidents.GetData().UtilityCode != utilityCode)
                    {
                        removedResidents.RemoveNode(removedResidents.GetNodeInterface());
                    }
                }
            }

            return removedResidents;
        }
        void ResidentsTable(ListNodes<Residents> residentsListNodes, int residentsChooser, string cheapestMonth)
        {
            var rowTop = new TableRow();

            for (int i = 0; i < 7; i++)
            {
                var cell = new TableCell();
                cell.BorderStyle = BorderStyle.Solid;
                cell.BorderWidth = 3;
                cell.Font.Size = 15;
                cell.Height = 30;
                cell.Width = 30;

                if (i == 0) cell.Text = "Pavarde";

                if (i == 1) cell.Text = "Vardas";

                if (i == 2) cell.Text = "Adresas";

                if (i == 3) cell.Text = "Menesis";

                if (i == 4) cell.Text = "Paslaugos kodas";

                if (i == 5) cell.Text = "Kiekis";

                if (i == 6) cell.Text = "Išleisti Pinigai";

                rowTop.Cells.Add(cell);
            }

            if (residentsChooser == 0)
            {
                Table2.Rows.Add(rowTop);

            }

            if (residentsChooser == 1)
            {
                Table3.Rows.Add(rowTop);

            }

            if (residentsChooser == 2)
            {
                Table4.Rows.Add(rowTop);

            }

            for (residentsListNodes.StartingNode(); residentsListNodes.Contains(); residentsListNodes.RightNode())
            {
                var row = new TableRow();

                for (int i = 0; i < 7; i++)
                {
                    var cell = new TableCell();
                    cell.BorderStyle = BorderStyle.Solid;
                    cell.BorderWidth = 3;
                    cell.Font.Size = 15;
                    cell.Height = 30;
                    cell.Width = 30;

                    if (i == 0) cell.Text = residentsListNodes.GetData().Surname;

                    if (i == 1) cell.Text = residentsListNodes.GetData().Name;

                    if (i == 2) cell.Text = residentsListNodes.GetData().Address;

                    if (i == 3) cell.Text = residentsListNodes.GetData().Month;

                    if (i == 4) cell.Text = residentsListNodes.GetData().UtilityCode;

                    if (i == 5) cell.Text = residentsListNodes.GetData().ServiceCount.ToString();

                    if (i == 6) cell.Text = residentsListNodes.GetData().MoneySpent.ToString();

                    row.Cells.Add(cell);
                }

                if (residentsChooser == 0) Table2.Rows.Add(row);
                if (residentsChooser == 1) Table3.Rows.Add(row);
                if (residentsChooser == 2) Table4.Rows.Add(row);
            }

            if (residentsChooser == 1)
            {
                var row = new TableRow();
                var cell = new TableCell();
                cell.Font.Size = 15;
                cell.Text = cheapestMonth;
                row.Cells.Add(cell);
                Table3.Rows.Add(row);
            }
        }