from datetime import  date

d1 = date(2017, 1, 4)
d2 = date(2017, 1, 31)

count = 0

for d_ord in range(d1.toordinal(), d2.toordinal()):
    d = date.fromordinal(d_ord)
    if (d.weekday() == 4):
        count += 1

print(count)