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First solution in Clear category for Unlucky Days by PawlakBartosz43
import datetime
def checkio(year):
out = 0
for i in [1,2,3,4,5,6,7,8,9,10,11,12]:
dz = datetime.datetime(year, i, 13, 0, 0, 0, 0).weekday()
if dz==4:
out+=1
return out
Jan. 15, 2017