weekday = [5]
month = (31, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30)

def leap_day(year):
    if not (year % 400):
        return 1
    if (year % 100) and (not (year % 4)):
        return 1
    return 0

for y in range(1900, 2001):
    for m in month:
        weekday.append((weekday[-1] + m) % 7)
        if 28 == m:
            weekday[-1] = (weekday[-1] + leap_day(y)) % 7

print(weekday[13:].count(0))