#3270 Suma Divizorilor Pari

#include <iostream>

using namespace std;

int main()
{
    int n;
    long long S = 0;
    cin >> n;
    for(int d = 1 ; d * d <= n ; d ++)
        if(n % d == 0)
        {
            if(d % 2 == 0)
                S += d;
            if(d * d < n )
                if(n / d % 2
                 == 0)
                    S += n / d;
        }

    cout << S;

    return 0;
}