//отсортировать недели по наименьшей загруженности
private IEnumerable <WeekInfo> GetSortedWeeksByCountLessons(ScheduleWeeks shedule)
{
return((from day in shedule.Days
group day by day.Week into grp
select new WeekInfo(grp.Key, grp.Sum(d => d.CountLessons))).OrderBy(day => day.CountLessons));
}