#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
using namespace std;

#define RREP(i,s,e) for (i = s; i >= e; i--)
#define rrep(i,n) RREP(i,n,0)
#define REP(i,s,e) for (i = s; i < e; i++)
#define rep(i,n) REP(i,0,n)
#define INF 100000000

typedef long long ll;

set<ll> divs;

void divisors(ll n) {
    ll i;
    for (i = 1; i * i <= n; i++) {
        if (n % i == 0) {
            divs.insert(i);
            divs.insert(n/i);
        }
    }
}

int main() {
    ll n, ans;
    cin >> n;
    if (n % 2 == 0)
        divisors(n/2);
    else
        divisors(n);
    ans = 0;
    for (auto x : divs)
        ans += x;
    cout << ans << endl;
    return 0;
}