cf1062D

#include<bits/stdc++.h>
#define forn(i, n) for (int i = 0 ; i < int(n) ; i++)
#define fore(i, s, t) for (int i = s ; i < (int)t ; i++)
#define fi first
#define se second
#define all(x) x.begin(),x.end()
#define pf2(x,y) printf("%d %d\n",x,y)
#define pf(x) printf("%d\n",x)
#define each(x) for(auto it:x)  cout<<it<<endl;
#define pii pair<int,int>
using namespace std;
typedef long long ll;
const int maxn=2e6+5;
const int maxm=2e5+5;
const int inf=1e9;
int main(){
	int n;
	cin>>n;
	ll ans=0;
	for(int i=2;i<=n;i++){
		for(int j=2;j*j<=i;j++){
			if(i%j) continue;
			ans+=j;
			if(j*j!=i) ans+=i/j;
		}
	}
	cout<<ans*4<<endl;
}