M = 10**6
prime = []
isPrime = [True]*(M+1)
isPrime[0] = isPrime[1] = False
for i in range(2, M):
  if isPrime[i]:
    prime.append(i)
    for j in range(i*i, M, i):
      isPrime[j] = False

N = int(input())
ans = 0
for p in prime:
  f = True
  for n in range(2, 60):
    if p**n > N: break
    f = False
    ans += p**n
  if f: break

print(ans)