fn main() {
	let mut s = String::new();
	std::io::stdin().read_line(&mut s).ok();
	let mut n: u64 = s.trim().parse().unwrap();
	let (mut a, mut i) = (0, 2);
	while i <= n {
		if i * i > n {
			a += n;
			break;
		}
		if n % i == 0 {
			n /= i;
			a += i;
		} else {
			i += 1;
		}
	}
	println!("{a}")
}