#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

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

const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

int main() {
	ll n; cin >> n;
	
	ll x;
	if (n & 1) x = n;
	else x = n / 2;
	
	ll ans = 0;
	
	for (ll i = 1; i * i <= x; ++i) {
		if (x % i == 0) {
			ans += i;
			if (i * i != x) ans += x / i;
		}
	}
	
	cout << ans << endl;
	
	return 0;
}