public bool IsValidYear(String year)
        {
            Regex objyr = new Regex("^([0-9]{4})-([0-9]{2})");
            return objyr.IsMatch(year);
        }

        public void checkyr()
        {
            if (IsValidYear(txtassyr.Text))
            {
                string[] strarry = txtassyr.Text.Split(' ');
                string temp;
                int i, j;
                foreach (string s in strarry)
                {
                    string[] str = s.Split('-');
                    temp = str[0].Substring(2);
                    i = Convert.ToInt32(temp);
                    j = Convert.ToInt32("1");
                    if (str[1].StartsWith("0"))
                    {
                        str[1] = str[1].Replace("0", "");
                    }
                    if (str[1].Equals(Convert.ToString(i + j)))
                    {
                        //
                    }
                    else
                    {
                        //MessageBox.Show(Convert.ToString(i + j));
                        MessageBox.Show("Please enter Ass-Year in following format 2008-09");
                        txtassyr.Text = "";
                        txtassyr.Focus();
                    }
                }
            }
            else
            {
                MessageBox.Show("Please enter Ass-Year in following format 2008-09");
                txtassyr.Text = "";
                txtassyr.Focus();
            }
        }