#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> lpair;
const ll MOD = 1e9 + 7;
const ll INF = 1e18;
#define rep(i,m,n) for(ll i = (m); i < (n); i++)
#define rrep(i,m,n) for(ll i = (m); i >= (n); i--)
#define print(x) cout << (x) << endl;
#define print2(x,y) cout << (x) << " " << (y) << endl;
#define printa(x,n) for(ll i = 0; i < n; i++){ cout << (x[i]) << " ";} cout<<endl;
ll val[2000010] = {};
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll N;
    cin >> N;
    rep(i,0,N/2){
        if(i % 2 == 0){
            val[i] = i+1;
            val[N-1-i] = N-i;
        }else{
            val[i] = N-i;
            val[N-1-i] = i+1;
        }
    }
    if(N % 2 == 1){
        val[N/2] = N/2 + 1;
    }
    ll ans = 0;
    rep(i,0,N-1) ans += val[i] * val[i+1];
    ans += val[N-1];
    print(ans);
    
}