#include <bits/stdc++.h>
using namespace std;
using ll     = long long;
using prefix = __attribute__((constructor))void;

const ll MOD = 1000000007;
const ll INF = 9223372036854775807LL;

#define elif       else if
#define def        inline auto
#define func       inline ll
#define lp(i,a,n)  for(ll i=(a),i##_1=(n);i<i##_1;++i)
#define rep(i,n)   lp(i,0,n)

func gcd(ll a,ll b) {return b?gcd(b,a%b):a;}
def  lcm(ll a,ll b) {return a*b/gcd(a,b);}
def  dig(ll a)      {return to_string(a).length();}
prefix init()      {cin.tie(0),ios::sync_with_stdio(0);}

signed main(){
  
  ll N,s=0;
  cin>>N;
  if(N==1){
    cout<<"0\n";
    return 0;
  }
  rep(i,N-1){
    if(i&1){
      s+=(N-i)*(i+2);
    }
    else{
      s+=(i+1)*(N-(i+1));
    }
  }
  if(!(N&1))s+=N/2;
  cout<<s+N<<"\n";
    
}