#include <bits/stdc++.h>
using namespace std;
int main(){
  long long N;
  cin>>N;
  int A[260000];
  for(int i=1;i<=N;i++)A[i]=0;
  for(int i=1;i<=N;i++){
    if(i%2==1){
      A[i]=i;
    }
    else {
      A[i]=N+1-i;
    }
  }
  long long answer=0;
  for(int i=1;i<=N-1;i++){
    answer=answer+A[i]*A[i+1];
  }
  answer=answer+A[N]*A[1];

}