from math import floor, sqrt

def main(n):
    ans = 0
    prime = [True] * (7500)
    x = [i for i in range(n + 1)]
    i = 2
    while i * i <= n:
        if prime[i]:
            w = i * i
            j = w

            while j * j <= n:
                prime[j] = False
                j += i

            j = w
            while j <= n:
                k = j
                while k <= n:
                    x[k] //= w
                    k += j
                j *= w
        i += 1
    for i in range(1, n + 1):
        ans += floor(sqrt(n / x[i]))
    print(ans)

n = int(input())
main(n)