def main():
    N = int(input())
    *A, = map(int, input().split())

    def f(x):
        a = 1
        for i in range(1, x+1):
            a *= i
        return a

    ans = f(N)

    for i in range(1, N+1):
        ans //= f(A.count(i))

    print(ans)


if __name__ == '__main__':
    main()