import itertools
from array import array


def isqrt(n):
    x = n
    y = (x + 1) // 2
    while y < x:
        x = y
        y = (x + n // x) // 2
    return x


def primes(n):
    is_prime = array("B", itertools.repeat(1, n + 1))
    is_prime[0] = 0
    is_prime[1] = 0
    for i in range(2, int(n ** 0.5) + 1):
        if not is_prime[i]:
            continue
        for j in range(i * 2, n + 1, i):
            is_prime[j] = 0
    return (i for i in range(n + 1) if is_prime[i])


N = int(input())
table = array("L", range(N + 1))
P = primes(N)
for p in P:
    p2 = p ** 2
    for x in range(p2, N + 1, p2):
        while not table[x] % p2:
            table[x] //= p2

ans = 0
for a in range(1, N + 1):
    ans += isqrt(N // table[a])
print(ans)