#!/usr/bin/ python3.8
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
import numpy as np
MOD = 10 ** 9 + 7


def cumprod(A, MOD=MOD):
    L = len(A)
    Lsq = int(L**.5 + 1)
    A = np.resize(A, Lsq**2).reshape(Lsq, Lsq)
    for n in range(1, Lsq):
        A[:, n] *= A[:, n - 1]
        A[:, n] %= MOD
    for n in range(1, Lsq):
        A[n] *= A[n - 1, -1]
        A[n] %= MOD
    return A.ravel()[:L]


def make_fact(U, MOD=MOD):
    x = np.arange(U, dtype=np.int64)
    x[0] = 1
    fact = cumprod(x, MOD)
    x = np.arange(U, 0, -1, dtype=np.int64)
    x[0] = pow(int(fact[-1]), MOD - 2, MOD)
    fact_inv = cumprod(x, MOD)[::-1]
    fact.flags.writeable = False
    fact_inv.flags.writeable = False
    return fact, fact_inv


N, *A = map(int, read().split())
counter = [0] * 5000
for x in A:
    counter[x] += 1


# 選ぶ人数 -> まともな包除ルールの選び方
dp = np.zeros(N + 1, np.int64)
dp[0] = 1
for x in counter[:N]:
    dp[1:] += dp[:-1] * x
    dp %= MOD

fact, fact_inv = make_fact(N + 1)
dp *= fact[::-1]
dp[1::2] *= (-1)
answer = (dp % MOD).sum() % MOD
print(answer)