#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>

#define REP(i,s,n) for(int i=(int)(s);i<(int)(n);i++)

using namespace std;
typedef long long int ll;
typedef vector<int> VI;
typedef pair<int, int> PI;
const double EPS=1e-9;



int main(void){
  ll n;
  cin >> n;
  if (n % 2 == 0) {
    n /= 2;
  }
  ll sum = 0;
  for (ll x = 1; x * x <= n; ++x) {
    if (n % x != 0) {
      continue;
    }
    sum += x;
    if (x * x != n) {
      sum += n / x;
    }
  }
  cout << sum << endl;
}