n = int(input())
def is_prime(n):
    if n <= 1:
        return False
    elif n <= 3:
        return True
    elif n % 2 == 0 or n % 3 == 0:
        return False
    i = 5
    while i * i <= n:
        if n % i == 0 or n % (i + 2) == 0:
            return False
        i += 6
    return True
s = 0
for i in range(2, 10 ** 5):
	if is_prime(i):
		j = 2
		while i ** j <= n:
			s += i ** j
print(s)