//https://ncode.syosetu.com/n4830bu/278/
#include <bits/stdc++.h>
using namespace std;
using ll = long long;

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