n=int(input())
ans=0
tmp=1
prime = [True for i in range(10**6+1)]
p = 2
k=n
if n<=10:
  k=100
while (p * p <= k):
  if (prime[p] == True):
    tmp*=p
    if tmp<=n:
      ans+=1
    else:
      exit(print(ans))
    for i in range(p * 2, 10**6+1, p):
      prime[i] = False
  p += 1
      



print(ans)