def Eratosthenes(n):
	table = [True]*(n+1)
	primes = []
	
	table[0],table[1] = False,False
	
	for i in range(2,n+1):
		if table[i]:
			primes.append(i)
			for j in range(2*i,n+1,i):
				table[j] = False
	
	return table, primes

# ================================

import math

N = int(input())
Nsq = math.isqrt(N)

_,primes = Eratosthenes(Nsq)

ans = 0
for p in primes:
  prod = p*p
  while prod <= N:
    ans += prod
    prod *= p
  
print(ans)