Sudoku.Form1.Box18_TextChanged C# (CSharp) Method

        private void Box18_TextChanged(object sender, EventArgs e)
        {
            int[,] arr = mapTableToArray(); CCC = new CheckCorrectCell(arr);
            if (CCC.checkCorrectCell9x9(1, 8) &&
                Box18.Text != "")
            {
                Box18.BackColor = Color.Red;
            }
            else
                Box18.BackColor = Color.White;
            congratulations9x9();
        }