MOD = 10**9 + 7

n = int(input())
A = [int(input()) for _ in range(n)]

from collections import defaultdict

cnt = defaultdict(int)
for a in A:
    cnt[a] += 1

vals = list(cnt.values())
m = len(vals)
max_k = min(m, n)

# Initialize dp array for elementary symmetric sums
dp = [0] * (max_k + 1)
dp[0] = 1

for c in vals:
    for k in range(min(m, max_k), 0, -1):
        dp[k] = (dp[k] + dp[k-1] * c) % MOD

# Precompute factorials modulo MOD
fact = [1] * (n + 1)
for i in range(1, n + 1):
    fact[i] = fact[i-1] * i % MOD

result = 0
for k in range(0, max_k + 1):
    if k > n:
        continue
    ek = dp[k]
    sign = 1 if k % 2 == 0 else MOD - 1
    term = (sign * ek) % MOD
    term = term * fact[n - k] % MOD
    result = (result + term) % MOD

print(result % MOD)