#include "bits/stdc++.h"
using namespace std;
#define print(x) cout<<x<<endl;
#define rep(i,a,b) for(int i=a;i<b;i++)
#define REP(i,a) for(int i=0;i<a;i++)
#define printall(n,array) {for(int i=0;i<n;i++){cout<<array[i]<<" ";}cout<<endl;}
#define U() cout<<endl;
typedef long long ll;
typedef pair<int, int> PI;
typedef pair<int, PI> V;
typedef vector<int> VE;
const ll mod = 1000000007; //10^9+7


vector<ll> enumdiv(ll n){
  vector<ll> s;
  for(ll i=1;i*i<=n;i++){
    if(n%i==0){
      s.push_back(i);
      if(i*i!=n)s.push_back(n/i);
    }
  }
  sort(s.begin(),s.end());
  return s;
}


int main(){
  ll n;
  cin>>n;
  ll u=0;
  if(n%2==0){
    u=n/2;
  }else{
    u=n;
  }
  vector<ll> v=enumdiv(u);
  ll ans=0;
  REP(i,v.size())ans+=v[i];
  print(ans);
}