#include <iostream>
using namespace std;

using int64 = long long;

int main() {
    int64 N;
    cin >> N;

    if (N % 2 == 0) N /= 2;
    int64 ans = 0;
    for (int64 n = 1; n * n <= N; n++) {
        if (N % n != 0) continue;
        int64 m = N / n;
        ans += n;
        if (n != m) ans += m;
    }
    cout << ans << endl;

    return 0;
}