MOD = 10 ** 9 + 7

n = int(input())
cnt = {}
for _ in range(n):
    a = int(input())
    cnt[a] = cnt.get(a, 0) + 1
dp = [0] * (n + 1)
dp[0] = 1

for v in cnt.values():
    for i in range(n, 0, -1):
        dp[i] += dp[i - 1] * v
        dp[i] %= MOD

fact = [1]
for i in range(1, n + 1):
    fact.append(fact[-1] * i % MOD)

ans = 0
pm = 1
for i, d in enumerate(dp):
    ans += pm * d * fact[n - i] % MOD
    pm *= -1
    ans %= MOD
print(ans)