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}.
def map_input(type=1):
    if type == 1:
        return map(int, input().split())
    elif type == 2:
        return map(float, input().split())
    elif type == 3:
        return map(str, input().split())
    return None


def list_input(type=1):
    return list(map_input(type))


def give_excel_column_name(r: int):
    l = 1
    r -= 1
    ans: str = ""
    while 26**l <= r:
        r -= 26**l
        l += 1
    while l > 0:
        ans += (chr(ord('A') + r//26**(l-1) % 26))
        l -= 1
    return ans


def give_excel_column_number(name: str):
    p = 1
    ans: int = 0
    for j in range(len(name)):
        ans = ans + p * ((ord(name[j]) - ord('A')) + 1)
        p = p * 26
    return ans


def sorted_indices(s):
    li = []
    for i in range(len(s)):
        li.append([s[i], i])
    li.sort()
    return [x[1] for x in li]

# https://www.geeksforgeeks.org/floor-in-a-sorted-array/


def floorSearch(arr, x, low=-1, high=-1):
    if low == -1:
        low = 0
    if high == -1:
        high == len(arr) - 1
    if (low > high):
        return -1
    if (x >= arr[high]):
        return high
    mid = int((low + high) / 2)
    if (arr[mid] == x):
        return mid
    if (mid > 0 and arr[mid-1] <= x
            and x < arr[mid]):
        return mid - 1
    if (x < arr[mid]):
        return floorSearch(arr, low, mid-1, x)
    return floorSearch(arr, mid + 1, high, x)


def find_index(arr, x):
    low = 0
    high = len(arr) - 1
    mid = 0
    while low <= high:
        mid = (high + low) // 2
        if arr[mid] < x:
            low = mid + 1
        elif arr[mid] > x:
            high = mid - 1
        else:
            return mid
    return -1


def floyd_warshell(g):
    n = len(g)
    d = g.copy()
    for k in range(n):
        for i in range(n):
            for j in range(n):
                d[i][j] = min(d[i][j], d[i][k] + d[k][j])
    return d


def int_input(type=1):
    if type == 1:
        return int(input())
    elif type == 2:
        return float(int(input()))


def range_input():
    return range(int_input())


def gcd(x, y):
    while(y):
        x, y = y, x % y
    return x


def is_prime(n):
    if n < 2:
        return False
    if n == 2:
        return True
    for i in range(2, int(n/2) + 1):
        if n % i == 0:
            return False
    return True


def main():
    n = int_input()
    fact = [1, 1]
    for i in range(2, 20):
        fact.append(fact[-1] * i)
    if n == 1:
        print(1)
    else:
        n = n * 2 - 2
        r = n//2
        print(int(fact[n]/(fact[n-r] * fact[r])))


if __name__ == "__main__":
    main()
    try:
        # main()
        pass
    except:
        pass
