Unlucky Days

*Friday 13th or Black Friday is considered as unlucky day. Calculate how many unlucky days are in the given year.*

Find the number of Friday 13th in the given year.

**Input: ** Year as an integer.

**Output: ** Number of Black Fridays in the year as an integer.

**Example:**

checkio(2015) == 3 checkio(1986) == 1

**Precondition:**
*1000 < |year| < 3000*