private void UsersGrid_CellEditEnded(object sender, Microsoft.Toolkit.Uwp.UI.Controls.DataGridCellEditEndedEventArgs e)
{
if (users[UsersGrid.SelectedIndex].Role != "Student")
{
users[UsersGrid.SelectedIndex].Group = "";
}
DataAccessClass.ChangeUserData(users[UsersGrid.SelectedIndex].Id, users[UsersGrid.SelectedIndex].Login, users[UsersGrid.SelectedIndex].Password, users[UsersGrid.SelectedIndex].Role, users[UsersGrid.SelectedIndex].Group);
}