for (int month = 1; month <= 12; month++)
Console.WriteLine($"Mês: {month}");
int daysInMonth = DateTime.DaysInMonth(year, month);
for (int day = 1; day <= daysInMonth; day++)
DateTime date = new DateTime(year, month, day);
Console.WriteLine($"{date:dd/MM/yyyy} - {date:dddd}");