#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <string>
#include <cstring>
#include <cstdint>
#include <vector>
#include <algorithm>
#include <cmath>
#include<iomanip>
#include <unordered_map>
#include <map>
using namespace std;
static const long long MOD = 1000000007LL;
typedef long long ll;
unordered_map <string,int> ump;
 
 
int main()
{
    ll n;
    cin>>n;
    ll sum=0;
    for(int i=1;i<=n/2;i++)
    {
    	if(n%i==0)
    		sum+=i;
    }
    cout<<sum<<endl;
    
    return 0;
}