# [開き括弧の個数, 今何番目]

N = int(input())
stack = []
stack.append([1, 1])
ans = 0
M = 2 * N
while stack:
    opened, cnt = stack.pop()
    if cnt == M:
        if opened == 0:
            ans += 1
        continue
    if opened - 1 >= 0:
        stack.append([opened - 1, cnt + 1])
    if M - (cnt + 1) >= opened + 1:
        stack.append([opened + 1, cnt + 1])

print(ans)