n = int(input())

DP = [[0 for _ in range(2 * n + 1)] for _ in range(2 * n)]
DP[0][1] = 1
for i in range(2 * n - 1):
    for j in range(2 * n):
        if DP[i][j] > 0:
            DP[i + 1][j + 1] += DP[i][j]
            if j - 1 >= 0:
                DP[i + 1][j - 1] += DP[i][j]
print(DP[-1][0])