An n × n table a is defined as follows:

  * The first row and the first column contain ones, that is: ai, 1 = a1, i = 1 for all i = 1, 2, ..., n. 
  * Each of the remaining numbers in the table is equal to the sum of the number above it and the number to the left of it. In other words, the remaining elements are defined by the formula ai, j = ai - 1, j + ai, j - 1. 



These conditions define all the values in the table.

You are given a number n. You need to determine the maximum value in the n × n table defined by the rules above.

Input

The only line of input contains a positive integer n (1 ≤ n ≤ 10) — the number of rows and columns of the table.

Output

Print a single line containing a positive integer m — the maximum value in the table.

Examples

Input

1


Output

1

Input

5


Output

70

Note

In the second test the rows of the table look as follows: 

{1, 1, 1, 1, 1},  {1, 2, 3, 4, 5},  {1, 3, 6, 10, 15},  {1, 4, 10, 20, 35},  {1, 5, 15, 35, 70}.
import java.util.Scanner;

/**
 * Created by frillyfrufru on 22/12/15.
 *
 * @codeforces.id A509
 * @codeforces.url http://codeforces.com/problemset/problem/509/A
 * @codeforces.keywords brute force, math, implementation
 * @codeforces.title Maximum in Table
 *
 * a[n][n] is defined as follows:
 *      (*) a[i][1] = a[1][i] = 1 for all i = 1,2,...,n
 *      (*) Each of the remaining elements are defined by
 *          a[i][j] = a[i-1][j] + a[i][j-1]
 *
 * Input:
 * A positive integer 1 <= n <= 10.
 * Output:
 * The maximum value in the table.
 *
 * Discussion
 * ==========
 * Well, a[][] is just a rotated Pascal's triangle whose rows
 * have been truncated at either end so as to fit in an n-by-n
 * grid.
 *
 * 1  1  1  1   1   1                      1
 * 1  2  3  4   5   6                   1     1
 * 1  3  6 10  15  21   ===>         1     2     1
 * 1  4 10 20  35  56             1     3     3     1
 * 1  5 15 35  70 126          1     4     6     4     1
 * 1  6 21 56 126 252       1     5    10     10    5     1
 *                       1     6    15     20    15    6     1
 *                    1     7    21    35     35    21    7     1
 *                 1     8    28    56    70     56    28    8     1
 *              1     9    36    84    126   126    84    36    9     1
 *            1   10    45    120   210   252   210    120   45   10     1
 *
 * which we can write in rectangular form as
 * 1
 * 1   1
 * 1   2   1
 * 1   3   3   1
 * 1   4   6   4   1
 * 1   5   10  10  5   1
 * 1   6   15  20 15   6   1
 * etc
 *
 * Row k of the triangle is
 *      binomial(k, 0), binomial(k, 1), binomial(k,2) ... binomial(k, k).
 * The maximum value runs down the middle of the triangle and is equal
 * to
 *      binomial(2n, n).
 * But this is exactly the value of a[n][n].
 *
 * For this problem in particular, we can just pre-compute the values of
 * binomial(2n, n) for 1 <= n <= 10 and stuff them in a table. Or you can
 * write the function binomial(n, r).
 */
public final class A509 {
    /** Do not instantiate. */
    private A509() {
    }

    public static void main(final String[] notUsed) {
        final int[] BINOMIAL_2N_N = {
                0, 1, 2, 6, 20, 70, 252, 924, 3432, 12870, 48620, 184756
        };

        System.out.println(BINOMIAL_2N_N[(new Scanner(System.in)).nextInt()]);

    }
}
