Define a period

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How many working days in year 2018?

Here is the detail of the calculation:

Because 2018 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 13 public holidays that do not fall during a weekend and we obtain 248 working days in 2018.

Here is the list of these 13 public holidays:

1. New Year's Day : Monday, 1 January, 2018
2. Coming of Age Day : Monday, 8 January, 2018
3. Foundation Day (observance) : Monday, 12 February, 2018
4. Vernal Equinox Day : Wednesday, 21 March, 2018
5. Shōwa Day (observance) : Monday, 30 April, 2018
6. Constitution Memorial Day : Thursday, 3 May, 2018
7. Greenery Day : Friday, 4 May, 2018
8. Marine Day : Monday, 16 July, 2018
9. Respect-for-Aged Day : Monday, 17 September, 2018
10. Autumnal Equinox Day (observance) : Monday, 24 September, 2018
11. Health and Sports Day : Monday, 8 October, 2018
12. Labor Thanksgiving Day : Friday, 23 November, 2018
13. Emperor's Birthday (observance) : Monday, 24 December, 2018

And here are the 7 public holidays falling on a weekend:

1. Foundation Day : Sunday, 11 February, 2018
2. Shōwa Day : Sunday, 29 April, 2018
3. Children's Day : Saturday, 5 May, 2018
4. Mountain Day : Saturday, 11 August, 2018
5. Autumnal Equinox Day : Sunday, 23 September, 2018
6. Culture Day : Saturday, 3 November, 2018
7. Emperor's Birthday : Sunday, 23 December, 2018