N = int(input())

MAXN = 10**5 + 5
sieve = [0,0] + [1]*MAXN
p = 2
while p*p <= MAXN:
    if sieve[p]:
        for q in range(2*p,MAXN+1,p):
            sieve[q] = 0
    p += 1

ans = 0
for p in range(2,MAXN):
    if sieve[p]:
        tmp = p
        while tmp*p <= N:
            tmp *= p
            ans += tmp
print(ans)