private void doublecellClick(object sender, DataGridViewCellEventArgs e)
{
var value = -1;
Int32.TryParse(dataGridView1.CurrentCell.FormattedValue.ToString(), out value);
if (value > -1 && selectInts.Contains(value))
{
selectInts.Remove(value);
}
if (old != null && !old.Equals(dataGridView1.CurrentCell))
{
old.Style.BackColor = Color.White;
}
dataGridView1.CurrentCell.Style.BackColor = Color.Red;
old = dataGridView1.CurrentCell;
startNum = value;
txtStart.Text = value + "";
txtExcept.Text = string.Join(",", selectInts);
dataGridView1.CurrentCell = null;
}