prime = [True] * (10 ** 5 + 1)

for i in range(2, int((10 ** 5) ** 0.5) + 1):
  if prime[i]:
    for j in range(i * 2, 10 ** 5 + 1, i):
      prime[j] = False

N = int(input())

ans = 0
for i in range(2, 10 ** 5 + 1):
  if prime[i]:
    j = i * i
    while j <= N:
      ans += j 
      j *= i

print(ans)