#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
using namespace std;

using ll = long long;
using P = pair<int, int>;
constexpr int INF = 1001001001;
// constexpr int mod = 1000000007;
constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;
    if(n == 1){
        cout << 0 << endl;
        return 0;
    }
    vector<int> ord(n);
    int l = 1, r = n, i = 0, j = n - 1;
    while(l <= r){
        if(l == r)  ord[i] = l++;
        else{
            if(i % 2 == 0){
                ord[i++] = l++;
                ord[j--] = r--;
            }
            else{
                ord[j--] = l++;
                ord[i++] = r--;
            }
        }
    }
    ll ans = 0;
    for(int i = 0; i < n; ++i){
        ans += (ll)ord[i] * ord[(i + 1) % n];
    }
    cout << ans << endl;

    return 0;
}