def solve():
    N = int(input())

    if N == 2:
        print(2)
        return

    ans = 2

    p = 1
    q = 1
    b = 3

    for i in range(2, N):
        x = p * 2

        for j in range(i):
            for k in range(j):
                x += (j+1) * (k+1) * q

        ans += x / b

        q *= i
        p *= (i+1)
        b *= (i+2)

    print(ans)


if __name__ == '__main__':
    solve()