#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v; ll w; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;
int INF = INT_MAX / 3;

int main() {
	int N; cin >> N;
	vector<int> a(5000);
	for (int i = 0; i < N; i++) {
		int A; cin >> A;
		a[A]++;
	}
	vector<int> dp(N + 1);
	dp[0] = 1;
	for (int i = 0; i < N; i++)
		for (int j = N - 1; j >= 0; j--)
			dp[j + 1] = (dp[j + 1] + (ll)dp[j] * a[i]) % MOD;
	vector<int> f(N + 1);
	f[0] = 1;
	for (int i = 1; i <= N; i++)
		f[i] = (ll)f[i - 1] * i % MOD;
	int ans = 0;
	for (int i = 0; i <= N; i++) {
		if (i % 2 == 0)
			ans = (ans + (ll)dp[i] * f[N - i]) % MOD;
		else
			ans = (ans - (ll)dp[i] * f[N - i]) % MOD;
	}
	cout << (ans + MOD) % MOD << endl;
}