#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define mp make_pair
#define pii pair<int,int>
#define all(v) v.begin(),v.end()

const int N = 1e4+4;
const int INF = 1E9+4;
const ll mod = 1e9+7;

int n,m;
int a[N],b[N];
vector<int>p;
vector<int>V[1000004];

int main(){

    ios::sync_with_stdio(false);
    cin.tie(0);

    cin>>n;
    ll ans = 0;
    for(int i=2;i<=n;++i){
        for(int j = i+i;j<=n;j+=i){
            ans += j/i;
        }
    }
    cout<<ans*4<<endl;
    return 0;
}