#include <algorithm>
#include <vector>
#include <cfloat>
#include <string>
#include <cmath>
#include <set>
#include <cstdlib>
#include <map>
#include <ctime>
#include <iomanip>
#include <functional>
#include <deque>
#include <iostream>
#include <cstring>
#include <queue>
#include <cstdio>
#include <stack>
#include <climits>
#include <sys/time.h>
#include <cctype>

using namespace std;

typedef long long ll;
typedef double d;

int main() {
  ll n;
  scanf("%lld", &n);
  ll x = n%2 ? n : n/2;
  ll cnt = 0;
  for (ll i = 1; i*i <= x; i++) {
    if (x%i) continue;
    cnt += i;
    if (i*i != x) {
      cnt += x/i;
    }
  }


  printf("%lld\n", cnt);
}