import math
n = int(input())
n_s = int(n**(1/2))

candidate = [i for i in range(2, n_s+1)] 
primes = []
limit = math.sqrt(n_s) + 1 

while True:
    p = min(candidate) 
    if limit <= p:
        primes.extend(candidate) 
        break
    primes.append(p) 

    candidate = [i for i in candidate if i % p != 0]

s = 0
i = 63
for p in primes:
    while p**i > n:
        i -= 1
    s += sum(list(p**j for j in range(2,i+1)))

print(s)