#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>
#include <complex>
#include <cassert>

using namespace std;

set<long long> factor;

void all_factor(long long n){
    factor.clear();
    for (long long i = 1; i*i <= n; i++){
        if (n % i == 0){
            factor.insert(i);
            factor.insert(n / i);
        }
    }
}

int main(){

    long long N, ans=0;
    cin >> N;
    if (N % 2 == 0) N /= 2;
    all_factor(N);
    for (auto x : factor) ans += x;
    cout << ans << endl;

    return 0;
}