Define a period

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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 11 public holidays that do not fall during a weekend and we obtain 250 working days in 1987.

Here is the list of these 11 public holidays:

1. New Year's Day : Thursday, 1 January, 1987
2. Seollal / Korean New Year Holiday : Wednesday, 28 January, 1987
3. Seollal / Korean New Year Holiday : Thursday, 29 January, 1987
4. Seollal / Korean New Year Holiday : Friday, 30 January, 1987
5. Independence Movement Day : Monday, 2 March, 1987
6. Children's Day : Tuesday, 5 May, 1987
7. Chuseok / Midautumn Festival : Tuesday, 6 October, 1987
8. Chuseok / Midautumn Festival : Wednesday, 7 October, 1987
9. Chuseok / Midautumn Festival : Thursday, 8 October, 1987
10. Hangeul Day : Friday, 9 October, 1987
11. Christmas Day : Friday, 25 December, 1987

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

1. Independence Movement Day : Sunday, 1 March, 1987
2. Memorial Day : Saturday, 6 June, 1987
3. Liberation Day : Saturday, 15 August, 1987
4. National Foundation Day : Saturday, 3 October, 1987