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}.
# -*- coding: utf-8 -*-
import sys
import math
import os
import itertools
import string
import heapq
import _collections
from collections import Counter
from collections import defaultdict
from functools import lru_cache
import bisect
import re
import queue
from decimal import *


class Scanner():
    @staticmethod
    def int():
        return int(sys.stdin.readline().rstrip())

    @staticmethod
    def string():
        return sys.stdin.readline().rstrip()

    @staticmethod
    def map_int():
        return [int(x) for x in Scanner.string().split()]

    @staticmethod
    def string_list(n):
        return [input() for i in range(n)]

    @staticmethod
    def int_list_list(n):
        return [Scanner.map_int() for i in range(n)]

    @staticmethod
    def int_cols_list(n):
        return [int(input()) for i in range(n)]


class Math():
    @staticmethod
    def gcd(a, b):
        if b == 0:
            return a
        return Math.gcd(b, a % b)

    @staticmethod
    def lcm(a, b):
        return (a * b) // Math.gcd(a, b)

    @staticmethod
    def divisor(n):
        res = []
        i = 1
        for i in range(1, int(n ** 0.5) + 1):
            if n % i == 0:
                res.append(i)
                if i != n // i:
                    res.append(n // i)
        return res

    @staticmethod
    def round_up(a, b):
        return -(-a // b)

    @staticmethod
    def is_prime(n):
        if n < 2:
            return False
        if n == 2:
            return True
        if n % 2 == 0:
            return False
        d = int(n ** 0.5) + 1
        for i in range(3, d + 1, 2):
            if n % i == 0:
                return False
        return True


class PriorityQueue:
    def __init__(self, l=[]):
        self.q = l
        heapq.heapify(self.q)
        return

    def push(self, n):
        heapq.heappush(self.q, n)
        return

    def pop(self):
        return heapq.heappop(self.q)


def pop_count(x):
    x = x - ((x >> 1) & 0x5555555555555555)
    x = (x & 0x3333333333333333) + ((x >> 2) & 0x3333333333333333)
    x = (x + (x >> 4)) & 0x0f0f0f0f0f0f0f0f
    x = x + (x >> 8)
    x = x + (x >> 16)
    x = x + (x >> 32)
    return x & 0x0000007f


MOD = int(1e09) + 7
INF = int(1e15)


def main():
    # sys.stdin = open("sample.txt")
    N = Scanner.int()
    A = [[0 for _ in range(N)]for _ in range(N)]
    for i in range(N):
        A[i][0] = 1
        A[0][i] = 1
    for i in range(1, N):
        for j in range(1, N):
            A[i][j] = A[i-1][j] + A[i][j-1]
    print(A[-1][-1])


if __name__ == "__main__":
    main()
