public static void Main()
DateTime nowDate = DateTime.Now;
int todayYear = nowDate.Year;
int yesterdayYear = nowDate.AddDays(-1).Year;
int todayDay = nowDate.Day;
int priorMonth = nowDate.AddMonths(-1).Month;
string targetYear = ((todayMonth == 1) && (todayDay == 1)) ? yesterdayYear.ToString() : todayYear.ToString();
Console.WriteLine($"todayDay: {todayDay}");
Console.WriteLine($"todayMonth: {todayMonth} vs priorMonth: {priorMonth}");
Console.WriteLine($"todayYear: {todayYear} vs yesterdayYear: {yesterdayYear}");
Console.WriteLine($"targetYear: {targetYear}");