n = int(input())
A = list(map(int, input().split()))
cnt = 0
dp = [0] * (1 << n)
max_ = [0] * (1 << n)
dp[0] = 1
for bit in range(1, 1 << n):
    for i in range(n):
        if bit >> i & 1:
            bbit = bit ^ (1 << i)
            if A[i] >= max_[bbit]:
                max_[bbit] = A[i]
                dp[bit] += dp[bbit]
x = dp[-1]
ans = 1
for i in range(1, n + 1):
    ans *= i
print(ans // x)