import numpy as np
N = int(input())
def get_sieve_of_eratosthenes(n):
    if not isinstance(n, int):
        raise TypeError("n is int-type.")
    if n < 2:
        raise ValueError("n is more than 2")
    data = [i for i in range(2, n + 1)]
    for d in data:
        data = [x for x in data if (x == d or x % d != 0)]
    return data
so = get_sieve_of_eratosthenes(N)
so = np.array(so)
ans = sum(so)
d = []
for i in range(N):
  a = so[i]
  if a in d:
    break
  if a* a> N:
    break
  b = a+0
  while b *a <=N:
    b =b*a
  c = so[so < N//a]
  try:
    c = c[-1]
  except:
    c =0
  if b-a < a*c-a-c:
    ans += a*c -a-c
    d.append(c)
  else:
    ans += b-a
print(ans)