Определить период

...

How many working days in year 1981?

Here is the detail of the calculation:

Because 1981 is not a leap year, it has 365 days.

Let's remove 52 saturdays and 52 sundays. It remains 261 days.

Now, let's remove 5 public holidays that do not fall during a weekend and we obtain 256 working days in 1981.

Here is the list of these 5 public holidays:

1. Jour de l'An : четверг, 1 январь, 1981
2. Vendredi Saint : пятница, 17 апрель, 1981
3. Jeudi de l'Ascension : четверг, 28 май, 1981
4. Fête-Dieu : четверг, 18 июнь, 1981
5. Noël : пятница, 25 декабрь, 1981

And here are the 4 public holidays falling on a weekend:

1. Fête nationale suisse : суббота, 1 август, 1981
2. Assomption : суббота, 15 август, 1981
3. Toussaint : воскресенье, 1 ноябрь, 1981
4. Saint Étienne : суббота, 26 декабрь, 1981