import sys
input = sys.stdin.readline

x=1000

import math 
L=math.floor(math.sqrt(x)) # 平方根を求める

Primelist=[i for i in range(x+1)]
Primelist[1]=0 # 1は素数でないので0にする.
 
for i in Primelist:
    if i>L:
        break
    if i==0:
        continue
    for j in range(2*i,x+1,i):
        Primelist[j]=0

Primes=[Primelist[j] for j in range(x+1) if Primelist[j]!=0]

A=[1]
for p in Primes:
    A.append(A[-1]*p)

N=int(input())
for i in range(len(A)):
    if N>=A[i]:
        ANS=i
print(ANS)