from math import sqrt, ceil, floor


def Sieve(n):
    lst = [True] * (n + 1)
    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 S

N = int(input())

P = Sieve(int(sqrt(N)) + 10)
L = list(range(N + 1))
for p in P:
    now = p * p
    while now <= N:
        for i in range(now, N + 1, now):
            L[i] //= p * p
        now *= p * p

ans = 0
for i in range(1, N + 1):
    ans += floor(sqrt(N//L[i]))

print(ans)