import java.io.*;
import java.util.*;
import java.util.Map.Entry;

@SuppressWarnings("unused")
public class Main {
	
	//final boolean isDebug = true;
	final boolean isDebug = false;
	String fileName = "input.txt";
	FastScanner sc;
	PrintWriter out;
	final int MOD = (int)1e9+7;
	//final int INF = Integer.MAX_VALUE / 2;
	final long INF = Long.MAX_VALUE / 2;
	
	void solve() throws Exception{
		int N = sc.nextInt();
		if(N == 1){
			System.out.println("0");
			return;
		}
		int[] a = new int[N];
		for(int i = 0; i < N; i++){
			if(i % 2 == 0) a[i] = 1 + 2 * (i / 2);
			else a[i] = N - 1 - 2 * (i / 2);
		}
		
		long sum = 0;
		for(int i = 0; i < a.length-1; i++){
			sum += a[i] * a[i+1];
		}
		sum += a[a.length-1] * a[0];
		System.out.println(sum);
	}
	
	/*
	void solve() throws Exception{
		int N = sc.nextInt();
		int[] a = new int[N];
		for(int i = 0; i < N; i++) a[i] = i+1;
		long min = Long.MAX_VALUE;
		do{
			long sum = 0;
			for(int i = 0; i < a.length-1; i++){
				sum += a[i] * a[i+1] + (a[i+1] - a[i]);
			}
			sum += a[a.length-1] * a[0] + (a[0] - a[a.length-1]);
			
			if(sum == 58){//true){
				System.out.print(sum + " : ");
				for(int e : a) System.out.print(e + " ");
				System.out.println();
			}
			min = Math.min(min, sum);
			//System.out.println(sum);
		}while(nextPermutation(a));
		System.out.println(min);
	}
	*/
	
	/* end solve */
	
	public static boolean nextPermutation(int[] a){
		for(int i = a.length - 1; i > 0; --i){
			if(a[i - 1] < a[i]){
				int swapIndex = find(a[i - 1], a, i, a.length - 1);
				int temp = a[swapIndex];
				a[swapIndex] = a[i - 1];
				a[i - 1] = temp;
				Arrays.sort(a, i, a.length);
				return true;
			}
		}
		return false;
	}

	/*
	 * 配列版
	 * destより大きい要素の中で最小のもののインデックスを二分探索で探す
	 */
	private static int find(int dest, int[] a, int s, int e){
		if(s == e){
			return s;
		}
		int m = (s + e + 1) / 2;
		return a[m] <= dest ? find(dest, a, s, m - 1) : find(dest, a, m, e);
	}
	
	/* main */
	public static void main(String[] args) throws Exception {
		new Main().m();
	}
	
	void m() throws Exception {
		long S = System.currentTimeMillis();
		sc = (isDebug) ? new FastScanner(new FileInputStream(fileName)) : new FastScanner(System.in);
		out = new PrintWriter(System.out);
		solve();
		out.flush();
		long G = System.currentTimeMillis();
		if(isDebug){
			System.out.println("---Debug---");
			System.out.printf("%8d ms\n", (G-S));
		}
	}
	/* end main */
}
/* end Main */

class CombCalculator{
	//引数の最大値、MOD、階乗・MODの逆元・階乗の逆元のテーブル
	static int MAX_FAC = 510000;
	static int MOD = (int)1e9+7;
	static long[] fac = new long[MAX_FAC+1];
	static long[] finv = new long[MAX_FAC+1];
	static long[] inv = new long[MAX_FAC+1];
	
	public CombCalculator(){
		this(510000, (int)1e9+7);
	}
	
	public CombCalculator(int max, int mod){
		MAX_FAC = max; MOD = mod;
		initComb();
	}
	
	//テーブルの初期化
	void initComb(){
		fac[0] = finv[0] = inv[0] = fac[1] = finv[1] = inv[1] = 1;
		for (int i = 2; i <= MAX_FAC; ++i) {
			fac[i] = fac[i - 1] * i % MOD;
			inv[i] = MOD - (MOD / i) * inv[(int) (MOD % i)] % MOD;
			finv[i] = finv[i - 1] * inv[i] % MOD;
		}
	}
	
	//nPk % MOD
	public long modPerm(int n, int k){
		return fac[n] * finv[n - k] % MOD;
	}
	
	//nCk % MOD
	public long modComb(int n, int k){
		return fac[n] * finv[k] % MOD * finv[n - k] % MOD;
	}
	
	//n! % MOD
	public long modFact(int n){
		return fac[n];
	}
	
	//(n!)^-1 % MOD
	public long modFactInv(int n){
		return finv[n];
	}
	
	//n^-1 % MOD
	public long modInv(int n){
		return inv[n];
	}
}

class FastScanner {
    private InputStream in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    public FastScanner(InputStream in) {
		this.in = in;
	}
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() {
    	if (hasNextByte()) return buffer[ptr++];
    	else return -1;
    }
    private static boolean isPrintableChar(int c){
    	return 33 <= c && c <= 126;
    }
    public boolean hasNext() {
    	while(hasNextByte() && !isPrintableChar(buffer[ptr]))
    		ptr++; return hasNextByte();
    }
    public String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public String nextLine() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(b != 10) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDouble() {
    	return Double.parseDouble(next());
    }
}