def main():
    N = int(input())
    N *= 2
    cnt = 0
    for i in range(1<<N):
        left = 0
        right = 0
        flag = True
        for j in range(N):
            if (i >> j) & 1:
                left += 1
            else:
                right += 1

            if right > left:
                flag = False
                break
        if flag and right == left:
            cnt += 1

    print(cnt)

if __name__ == "__main__":
    main()