from math import isqrt


def sieve(n: int):
    """エラトステネスの篩（O(n log log n)）"""
    is_prime = [True] * (n + 1)
    is_prime[0] = is_prime[1] = False
    for i in range(2, isqrt(n) + 1):
        if is_prime[i]:
            for j in range(i * i, n + 1, i):
                is_prime[j] = False
    return [i for i in range(n + 1) if is_prime[i]]


N = int(input())
primes = sieve(isqrt(N))

ans = 0

for e in range(2, 40):
    for p in primes:
        if p**e > N:
            break
        ans += p**e

print(ans)