private void button1_Click(object sender, EventArgs e)
{
CourseManageAction.controllAmount(lvSIC, label5.Text);
label8.Text = CourseManageAction.NumberInClass(label5.Text).ToString() + "/" + CourseManageAction.getAmount(label5.Text).ToString();
CourseManageAction.loadStudentInClass(lvSIC, label5.Text);
}