#include <bits/stdc++.h>
#define ll long long 
#define nhanh  ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define fip freopen("SHH.INP","r",stdin)
#define fout freopen("SHH.OUT","w",stdout)
#define gop fip;fout;nhanh ;
#pragma GCC optimize("O2")
bool check_hhao(ll n){
    ll s = 0 ;
    for (ll i=1;i<=n/2;i++) if (n%i==0) s += i ;
    return (s==n);
}
using namespace std;
int main(){
    gop ;
    ll n ; cin >> n ;
    ll s = 0 ; 
    for (ll i=1;i<=n;i++) if (check_hhao(i)) s += i ;
    cout << s ;
}