l = 10 ** 5
isp = [1] * l
for i in range(2, l):
  if not isp[i]:
    continue
  for j in range(i*i, l, i):
    isp[j] = 0

n = int(input())
ans = 0
for p in range(2, l):
  if not isp[p]:
    continue
  x = p ** 2
  while x <= n:
    ans += x
    x *= p
print(ans)