AI_Project_3.MainPage.AddtoSchedule_Click C# (CSharp) Method

        private void AddtoSchedule_Click(object sender, RoutedEventArgs e)
        {
            int selectedItem = this.AllClasses.SelectedIndex;

            if (selectedItem >= 0)
            {
                Class c = majorinit.listOfAllClasses.ElementAt(selectedItem);

                //Checks if the class is currently in the schedule, if found, remove it
                foreach (Year y in majorinit.scheduleOfClasses)
                {
                    foreach (Quarter q in y.Quarters)
                    {
                        if (q.getClasses.Contains(c))
                            q.getClasses.Remove(c);
                    }
                }

                //Adds class to the selected quarter and updates
                _CollectionOfClassesForSelectedQuarter.Add(c);
                _SelectedQuarter.ItemsSource = _CollectionOfClassesForSelectedQuarter;
            }
        }