from math import isqrt

n = int(input())

# ~sqrt(N)の素数

MAX = isqrt(n)
sieve = list(range(MAX + 1))
sieve[1] = 0

for i in range(isqrt(MAX) + 1):
    if sieve[i] != 0:
        for j in range(i + i, MAX + 1, i):
            sieve[j] = 0

primes = [pi for pi in sieve if pi != 0]
ans = 0
for p in primes:
    x = p * p
    while x <= n:
        ans += x
        x *= p
print(ans)