from math import isqrt

def eratosthenes(n):
    sieve = [True] * (n + 1)
    for i in range(int(n**0.5) + 1):
        if i < 2:
            sieve[i] = False
        elif sieve[i]:
            for j in range(2, n//i + 1):
                sieve[i * j] = False
    ans = []
    for i in range(n+1):
        if sieve[i]:
            ans.append(i)
    return ans

N = int(input())

E = eratosthenes(isqrt(N))
ans = 0
for e in E:
    n = e**2
    while n <= N:
        ans += n
        n *= e

print(ans)