Define a period

...

How many working days in year 1987?

Here is the detail of the calculation:

Because 1987 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 10 public holidays that do not fall during a weekend and we obtain 251 working days in 1987.

Here is the list of these 10 public holidays:

1. Πρωτοχρονιά : Thursday, 1 January, 1987
2. Θεοφάνεια : Tuesday, 6 January, 1987
3. Καθαρά Δευτέρα : Monday, 2 March, 1987
4. Εικοστή Πέμπτη Μαρτίου : Wednesday, 25 March, 1987
5. Μεγάλη Παρασκευή : Friday, 17 April, 1987
6. Δευτέρα του Πάσχα : Monday, 20 April, 1987
7. Εργατική Πρωτομαγιά : Friday, 1 May, 1987
8. Δευτέρα Πεντηκοστής : Monday, 8 June, 1987
9. Ημέρα του Όχι : Wednesday, 28 October, 1987
10. Χριστούγεννα : Friday, 25 December, 1987

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

1. Ορθόδοξο Πάσχα : Sunday, 19 April, 1987
2. Πεντηκοστή : Sunday, 7 June, 1987
3. Κοίμηση της Θεοτόκου : Saturday, 15 August, 1987
4. Σύναξη της Θεοτόκου : Saturday, 26 December, 1987