private void buttonCheat_Click(object sender, EventArgs e)
        {
            FormForUsers form = new FormForUsers(GetObject().student[listBoxUsers.SelectedIndex]);

            if (form.ShowDialog(this) == DialogResult.OK)
            {
                var student = GetObject();
                listBoxUsers.Items[listBoxUsers.SelectedIndex] = form.GetObject();
            }
        }
        private void buttonAddUser_Click(object sender, EventArgs e)
        {
            var form = new FormForUsers();

            if (form.ShowDialog(this) == DialogResult.OK)
            {
                listBoxUsers.Items.Add(form.GetObject());
            }
            ProverkaNalichia();
        }