Определить период

...

How many working days in year 1991?

Here is the detail of the calculation:

Because 1991 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 9 public holidays that do not fall during a weekend and we obtain 252 working days in 1991.

Here is the list of these 9 public holidays:

1. New Year's Day : вторник, 1 январь, 1991
2. Maundy Thursday : четверг, 28 март, 1991
3. Good Friday : пятница, 29 март, 1991
4. Easter Monday : понедельник, 1 апрель, 1991
5. General Prayer Day : пятница, 26 апрель, 1991
6. Ascension Day : четверг, 9 май, 1991
7. Whit Monday : понедельник, 20 май, 1991
8. Christmas Day : среда, 25 декабрь, 1991
9. Boxing Day : четверг, 26 декабрь, 1991

And here are the 2 public holidays falling on a weekend:

1. Easter Sunday : воскресенье, 31 март, 1991
2. Pentecost : воскресенье, 19 май, 1991