5

d = int(input())
n = 8
s = 6
while s <= 1800:
    s = s + d
    n = n + 7
print(n)

#n+7k = 238
#k = 34
#s + d*(k-1)<=1800
#s*d*k > 1800

#6 + 33d <= 1800
#6 + 34d > 1800

#33d <= 1794    d == 54.36363636363637
#34d > 1794     d == 52.76470588235294

#d == 53,54