You are given a regular polygon with n vertices labeled from 1 to n in counter-clockwise order. The triangulation of a given polygon is a set of triangles such that each vertex of each triangle is a vertex of the initial polygon, there is no pair of triangles such that their intersection has non-zero area, and the total area of all triangles is equal to the area of the given polygon. The weight of a triangulation is the sum of weigths of triangles it consists of, where the weight of a triagle is denoted as the product of labels of its vertices.

Calculate the minimum weight among all triangulations of the polygon.

Input

The first line contains single integer n (3 ≤ n ≤ 500) — the number of vertices in the regular polygon.

Output

Print one integer — the minimum weight among all triangulations of the given polygon.

Examples

Input


3


Output


6


Input


4


Output


18

Note

According to Wiki: polygon triangulation is the decomposition of a polygonal area (simple polygon) P into a set of triangles, i. e., finding a set of triangles with pairwise non-intersecting interiors whose union is P.

In the first example the polygon is a triangle, so we don't need to cut it further, so the answer is 1 ⋅ 2 ⋅ 3 = 6.

In the second example the polygon is a rectangle, so it should be divided into two triangles. It's optimal to cut it using diagonal 1-3 so answer is 1 ⋅ 2 ⋅ 3 + 1 ⋅ 3 ⋅ 4 = 6 + 12 = 18.
import java.util.*;
import java.math.*;

// **** D. Minimum Triangulation ****

public class D {
	static char [] in = new char [100000];
	public static void main (String [] arg) throws Throwable {
		int n = nextInt();
		long ans = 0;
		for (int i = 2; i<n; ++i) {
			ans += 1 * i * (i+1);
		}
		System.out.println(ans);
	}

	
	
	
	
	
	
	
	
	
	
	
	
	
	
	/************** FAST IO CODE FOLLOWS *****************/
	public static long nextLong() throws Throwable {
		long i = System.in.read();boolean neg = false;while (i < 45) i = System.in.read();if (i == 45) {neg=true;i=48;}i = i - 48;
		int j = System.in.read();while (j > 32) {i*=10;i+=j-48;j = System.in.read();}return (neg) ? -i : i;
	}
	public static int nextInt() throws Throwable {return (int)nextLong();}
	public static String next() throws Throwable {
		int i = 0; while (i < 42 && i != -1) i = System.in.read(); int cptr = 0; while (i >= 42) { in[cptr++] = (char)i; i = System.in.read();}
		return new String(in, 0,cptr);
	}
	/**** LIBRARIES ****/
	public static long gcdL(long a, long b) {while (b != 0) {long tmp = b;b = (a % b);a = tmp;}return a;}
	public static int gcd(int a, int b) {while (b != 0) {int tmp = b;b = (a % b);a = tmp;}return a;}
	public static int[] sieve(int LIM) {
		int i,count = 0;
		boolean [] b = new boolean [LIM];
		for (i = 2;i<LIM; ++i) if (!b[i]) {count++; for (int j = i<<1; j<LIM; j+=i) b[j] = true;}
		int [] primes = new int[count];
		for (i = 2,count=0;i<LIM;++i) if (!b[i]) primes[count++] = i;
		return primes;
	}
	public static int[] numPrimeFactors(int LIM) {
		int i,count = 0;
		int [] b = new int [LIM];
		for (i = 2;i<LIM; ++i) if (b[i] == 0) {count++; for (int j = i; j<LIM; j+=i) b[j]++;}
		return b;
	}
}

/* Full Problem Text:
  
You are given a regular polygon with n vertices labeled from 1 to n in counter-clockwise order.
The triangulation of a given polygon is a set of triangles such that each vertex of each triangle is a vertex of the initial polygon, there is no pair of triangles such that their intersection has non-zero area, and the total area of all triangles is equal to the area of the given polygon.
The weight of a triangulation is the sum of weigths of triangles it consists of, where the weight of a triagle is denoted as the product of labels of its vertices.
Calculate the minimum weight among all triangulations of the polygon.

 */