def is_prime(x):
    if x < 2:
        return False
    for i in range(2, int(x**0.5)+1):
        if x % i == 0:
            return False
    return True

n = int(input())

ans = set()

for i in range(2, int(n**0.5)+1):
    if is_prime(i):
        power = i * i
        while power <= n:
            ans.add(power)
            power *= i

print(sum(ans))