#include<iostream>
#include<vector>
#include<set>
#include<map>
#include<list>
#include<stack>
#include<bitset>
#include<array>
#include<algorithm>
#include<cstdio>
#include<string>
#include<cstdlib>
#define D long long
#define U unsigned
using namespace std;
D n, m,a, b, d, e, x, y, z;
D i, j, k;
int main() {
	cin >> a;
	for (i = 1; i <= a; i+=2) {
		if (a%i == 0)
			n+=i;
	}
	cout << n << endl;
}