import itertools


n = int(input())

answer = 0
for pops in itertools.combinations(range(2 * n), n):
    pops_set = set(pops)
    s = 0
    criteria = True
    for i in range(2 * n):
        if i in pops_set:
            s += 1
        else:
            s -= 1
        if s < 0:
            criteria = False
            break
    if criteria:
        answer += 1
print(answer)