Define a period

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How many working days in year 1980?

Here is the detail of the calculation:

Because 1980 is a leap year, it has 366 days.

Let's remove 52 saturdays and 52 sundays. It remains 262 days.

Now, let's remove 11 public holidays that do not fall during a weekend and we obtain 251 working days in 1980.

Here is the list of these 11 public holidays:

1. Solenidade da Santa Mãe de Deus : Tuesday, 1 January, 1980
2. Sexta-Feira Santa : Friday, 4 April, 1980
3. Dia da Liberdade : Friday, 25 April, 1980
4. Dia do Trabalhador : Thursday, 1 May, 1980
5. Corpo de Deus : Thursday, 5 June, 1980
6. Dia de Portugal : Tuesday, 10 June, 1980
7. Dia de São João : Tuesday, 24 June, 1980
8. Assunção de Nossa Senhora : Friday, 15 August, 1980
9. Restauração da Independência : Monday, 1 December, 1980
10. Dia da Imaculada Conceição : Monday, 8 December, 1980
11. Natal : Thursday, 25 December, 1980

And here are the 3 public holidays falling on a weekend:

1. Páscoa : Sunday, 6 April, 1980
2. Implantação da República : Sunday, 5 October, 1980
3. Todos os Santos : Saturday, 1 November, 1980