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Second solution in Clear category for Unlucky Days by Gaydar
def checkio(year):
import calendar
return sum(1 for i in range(1,13) if calendar.weekday(year,i,13)==4)
if __name__ == '__main__':
#These "asserts" using only for self-checking and not necessary for auto-testing
assert checkio(2015) == 3, "First - 2015"
assert checkio(1986) == 1, "Second - 1986"
April 15, 2016