days = [31,28,31,30,31,30,31,31,30,31,30,31]
leap = lambda rok: (rok % 4 == 0 and rok % 100 != 0) or rok % 400 == 0

def mdays(year, month):
    if month == 1 and leap(year):
        return 29
    else:
        return days[month]

year, month, day = 2000, 0, 6 #7 stycznia 2000, pierwszy piatek roku
stop = 1000000000

p = 0
l = 0

while year < stop:
    l += [365, 366][leap(year)]
    while month < 12:
        while day < mdays(year, month):
            if day == 12:
                #print("year: %d month: %d day: %d" % (year, month, day))
                p += 1
            day += 7
        day = (day + 7) % mdays(year, month)
        month += 1
    month = 0
    year += 1

print (p/l)