import datetime

n = int(input())
count = 0
# 2014-12-25 is a Thursday, which is 3 in weekday() (Monday=0)
target_weekday = datetime.date(2014, 12, 25).weekday()

for year in range(2015, n + 1):
    if datetime.date(year, 12, 25).weekday() == target_weekday:
        count += 1

print(count)