# 自作ライブラリ
# https://github.com/takumi-okamoto/competitive-programming-public/tree/main/mylib

import sys


# sys.setrecursionlimit(10**8)


def debug(*args):
    print(*args, file=sys.stderr)


def sieve_of_eratosthenes(limit: int) -> list[int]:
    sieve = [True] * (limit + 1)
    sieve[0] = sieve[1] = False
    for start in range(2, int(limit**0.5) + 1):
        if sieve[start]:
            for i in range(start * start, limit + 1, start):
                sieve[i] = False
    return [num for num, is_prime in enumerate(sieve) if is_prime]


def main():
    n = int(input())
    primes = sieve_of_eratosthenes(int(n**0.5) + 2)
    ans = 0
    for p in primes:
        x = p * p
        while x <= n:
            ans += x
            x *= p

    print(ans)


if __name__ == "__main__":
    main()