from itertools import combinations
N = int(input())
ans = 0
for z in combinations(range(2*N),N):
    flag = True
    j = 0
    A = []
    for i in range(2*N):
        if j==N:break
        if z[j]==i:
            A.append(1)
            j += 1
        else:
            if len(A)==0:
                flag = False
                break
            A.pop()
    if flag:
        ans += 1
print(ans)