private void days(object sender, DataGridViewCellFormattingEventArgs e)
    {
        var senderGrid = (DataGridView)sender;
        if (senderGrid.Columns[e.ColumnIndex] is DataGridViewButtonColumn && e.RowIndex >= 0)
        {
            var c = SmanArea.Rows[e.RowIndex].Cells[e.ColumnIndex];
            if (c.Value.ToString() == "1" && c is DataGridViewButtonCell)
            {
                c.Style.BackColor = Color.LightGreen;
            }
            else
            {
                c.Style.BackColor = Color.RosyBrown;
            }
        }
    }