def readint():
    return map(int, input().split())


def sieve(n):
    isprime = [True] * (n + 1)
    res = []
    isprime[0] = isprime[1] = False
    for i in range(2, n + 1):
        if not isprime[i]:
            continue
        else:
            res.append(i)
            for j in range(i * i, n + 1, i):
                isprime[j] = False
    return res


from math import isqrt

n = int(input())
p = sieve(isqrt(n))
ans = 0
for i in range(len(p)):
    syoko = p[i] * p[i]
    if syoko > n:
        break
    makko = syoko
    kosu = 1
    while makko <= n:
        makko *= p[i]
        kosu += 1
    makko //= p[i]
    kosu -= 1
    ans += (syoko * (p[i] ** kosu - 1)) // (p[i] - 1)
print(ans)