static void Main(string[] args) { var ymCollection = new Exercise1.YearMonth[] { new Exercise1.YearMonth(1980, 1), new Exercise1.YearMonth(1990, 4), new Exercise1.YearMonth(2000, 7), new Exercise1.YearMonth(2010, 9), new Exercise1.YearMonth(2020, 12), }; Exercise2_2(ymCollection); Console.WriteLine("------------"); Exercise2_4(ymCollection); Console.WriteLine("------------"); Exercise2_5(ymCollection); Console.WriteLine("------------"); }