#include <bits/stdc++.h>

using namespace std;

typedef vector<int> vi;
typedef pair<int,int> ii;
typedef long long ll;

int main()
{
    ll n;
    cin>>n;
    if(n%2==0)
        n/=2;
    ll rez=0;
    for(ll ctr1=1;ctr1*ctr1<=n;ctr1++){
        if(ctr1*ctr1==n) {rez+=ctr1;continue;}
        if(n%ctr1==0)
            rez+=ctr1+n/ctr1;
    }
    cout<<rez<<endl;
    return 0;
}