#include <iostream>
#include <map>
#include <set>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <complex>
#include <cstdlib>
#include <cstring>
#include <numeric>
#include <sstream>
#include <algorithm>
#include <functional>
#include <limits.h>
#include <bitset>

#include <tuple>
#include <unordered_map>

#define mp       make_pair
#define mt       make_tuple
#define pb       push_back
#define rep(i,n) for(int i=0;i<(n);i++)

using namespace std;

typedef    long long          ll;
typedef    unsigned long long ull;
typedef    pair<int,int>      pii;

const int INF=1<<29;
const double EPS=1e-9;

const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
ll n;
ll calc(ll x){
  ll res = 0;
  for (ll i = 1; i * i <= x; i++){
    if (x % i == 0){
      res += i;
    }
    if (i * i != x){
      res += x / i;
    }
  }
  return res;
}
int main(){
  cin >> n;
  if (n % 2 == 0){
    n = n / 2;
  }
  cout << calc(n) << endl;
}