#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int v; ll w; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-8;
int INF = INT_MAX / 2;

int main() {
	ll N; cin >> N;
	if (N % 2 == 0) N /= 2;
	ll sum = 0;
	for (ll i = 1; i * i <= N; i++)
		if (N % i == 0) {
			sum += i;
			if (i * i < N) sum += N / i;
		}
	cout << sum << endl;
}