#include <iostream>
#include <cstdio>
#include <cmath>

using namespace std;

int main() {
	long long n, ans = 0;

	cin >> n;
	// sum = k + (k + 1) + (k + 2) + ... + (k + (n - 1))
	//     = nk + n(n - 1)/2
	//     = n(k + (n - 1)/2 )

	if (n % 2 == 0) {
		n /= 2;
	}

	long long limit = sqrt(n);
	for (long long i = 1; i <= limit; i++) {
		if (n % i == 0) {
			ans += i + n / i;
		}
	}
	if (n == limit * limit) {
		ans -= limit;
	}

	cout << ans << endl;
	return 0;
}