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 = [True] * (n + 1)
    is_prime[0] = False
    is_prime[1] = False
    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] = False
    return (i for i in range(n + 1) if is_prime[i])


def main():
    N = int(input())
    table = list(range(N + 1))
    for p in primes(N):
        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)


main()