#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; }