Can I place only integers on Y axis of Ajax Line Chart in asp Please Help me

public void BindChart()
    {
        string query = string.Format("Select SubjectID,GradeID from dbo.tbl_StudentGrades where StudentID=1001 and TestID=1", "1001");
        DataTable dt = GetData(query);

        string[] x = new string[dt.Rows.Count];
        Decimal[] y = new Decimal[dt.Rows.Count];
        for (int i = 0; i < dt.Rows.Count; i++)
        {
            x[i] = dt.Rows[i][0].ToString();
            y[i] =  Convert.ToInt32(dt.Rows[i][1]);
        }
        LineChart1.Series.Add(new AjaxControlToolkit.LineChartSeries { Data = y });        
        LineChart1.CategoriesAxis = string.Join(",", x);        
        LineChart1.ChartTitle = string.Format("Student Status Subjectwise", "StudentID");
        if (x.Length > 3)
        {
            LineChart1.ChartWidth = (x.Length * 75).ToString();
        }
        LineChart1.Visible = true;
    }

    private static DataTable GetData(string query)
    {
        DataTable dt = new DataTable();
        string constr = "Data Source=xxxxx;Initial Catalog=sss;Persist Security Info=True;User ID=sasasa;Password=asasasas";
        using (SqlConnection con = new SqlConnection(constr))
        {
            using (SqlCommand cmd = new SqlCommand(query))
            {
                using (SqlDataAdapter sda = new SqlDataAdapter())
                {
                    cmd.CommandType = CommandType.Text;
                    cmd.Connection = con;
                    sda.SelectCommand = cmd;
                    sda.Fill(dt);
                }
            }
            return dt;
        }
    }