#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}

//INSERT ABOVE HERE
signed main(){
  Int n;
  cin>>n;
  Int a=n&1?n:n/2;
  Int x=0;
  for(Int i=1;i*i<=a;i++){
    if(a%i) continue;
    x+=i;
    if(i*i!=a) x+=a/i;
  }
  cout<<x<<endl;
  return 0;
}