N = int(input())

def calc(now = 1,count = 0):
    if now == N * 2:
        if count == 1:
            return 1
        else:
            return 0
    ans = 0
    ans += calc(now + 1,count + 1)
    if count > 0:
        ans += calc(now + 1,count - 1)
    return ans
print(calc())