import math

# エラトステネスの篩
def prime(n):
    is_prime = [True] * (n + 1)
    is_prime[0], is_prime[1] = False, False
    for i in range(2, int(math.sqrt(n)) + 1):
        if is_prime[i]:
            for j in range(2 * i, n + 1, i):
                is_prime[j] = False
    return is_prime

import sys
input = sys.stdin.readline
N = int(input())
P = prime(int(math.sqrt(N))+1)
ans = 0
for p, f in enumerate(P):
    if f==False:
        continue
    e = 2
    while p**e<=N:
        ans += p**e
        e+=1
print(ans)