n = int(input())
out = 0
def is_prime(number):
global boolnum
primeCount = 0
for i in range(1, (int(number/2))+1):
if number % i == 0:
primeCount += 1
if primeCount == 1:
boolnum = True
else:
boolnum = False
for each in range(n-2):
is_prime(each)
if boolnum == True:
out += 1
print(out)