#include <iostream>
using namespace std;
int n,d,s;
int main()
{
    cin>>n;
    for(d=1;d*d<n;d++)
    {
        if(n%d==0)
         {
             if(d%2==1) s=s+d;
             if((n/d)%2==1) s=s+n/d;
         }
    }
    if((d*d==n)&&(d%2==1)) s=s+d;
    cout<<s;
    return 0;
}