#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(nullptr);
    ll N;
    cin >> N;
    if(N%2==0)N/=2;
    ll ans=0;
    for(ll d=1;d*d<=N;d++) {
        if(N%d==0) {
            ans+=d;
            if(d*d<N)ans+=N/d;
        }
    }
    cout<<ans<<"\n";
}