using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        if (n == 1)
        {
            WriteLine(0);
            return;
        }
        var from = new int[n];
        for (var i = 0; i < n; ++i) from[i] = i + 1;
        var to = new long[n];
        to[0] = 1;
        var fl = 1;
        var fr = n - 1;
        var tl = 1;
        var tr = n - 1;
        while (fl <= fr)
        {
            to[tl] = from[fr];
            --fr;
            ++tl;
            if (fl > fr) break;
            to[tr] = from[fr];
            --fr;
            --tr;
            if (fl > fr) break;
            to[tl] = from[fl];
            ++fl;
            ++tl;
            if (fl > fr) break;
            to[tr] = from[fl];
            ++fl;
            --tr;
        }
        var ans = 0L;
        for (var i = 0; i < n; ++i) ans += to[i] * to[(i + 1) % n];
        WriteLine(ans);
    }
    static void Permutate(int n, Action<int[]> action)
    {
        var seed = new int[n];
        for (var i = 0; i < n; ++i) seed[i] = i;
        var used = new bool[n];
        var perm = new int[n];
        Permutate(0, seed, perm, used, action);
    }
    static void Permutate(int pos, int[] seed, int[] perm, bool[] used, Action<int[]> action)
    {
        if (pos == used.Length) action(perm);
        for (var i = 0; i < used.Length; ++i)
        {
            if (used[i]) continue;
            perm[pos] = seed[i];
            used[i] = true;
            Permutate(pos + 1, seed, perm, used, action);
            used[i] = false;
        }
    }
}