from math import ceil, sqrt
def Sieve(n):
    lst = [True] * (n + 1)
    lst[0] = lst[1] = False
    S = set()
    for i in range(2, ceil(sqrt(n)) + 1):
        if lst[i]:
            for j in range(2 * i, n + 1, i):
                lst[j] = False
    for i in range(2, n + 1):
        if lst[i]:
            S.add(i)
    return sorted(list(S))

N = int(input())
S = Sieve(10**6)
v, c = 1, 0
S.reverse()
while v * S[-1] <= N:
    v *= S.pop()
    c += 1
    
print(c)