#include<iostream>
#include<cstdio>
#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cctype>
#include<cstdlib>
#include<algorithm>
#include<bitset>
#include<vector>
#include<list>
#include<deque>
#include<queue>
#include<map>
#include<set>
#include<stack>
#include<cmath>
#include<sstream>
#include<fstream>
#include<iomanip>
#include<ctime>
#include<complex>
#include<functional>
#include<climits>
#include<cassert>
#include<iterator>
#include<unordered_map>
using namespace std;
#define MOD 1000000007
#define MAX 5001
int cnt[MAX];
int n;
vector<long long int> cn;
int dp[MAX][MAX];
long long int k[MAX];
long long int ppow(long long int i, long long int j){
	long long int r = 1LL;
	while (j){
		if ((j & 1LL)){
			r *= i;
			r %= MOD;
		}
		i *= i;
		i %= MOD;
		j >>= 1LL;
	}
	return r;
}
int main(){
	scanf("%d", &n);
	k[0] = 1LL;
	for (int i = 1; i < MAX; i++){
		k[i] = k[i - 1];
		k[i] *= (long long int)(i);
		k[i] %= MOD;
	}
	for (int i = 0; i < n; i++){
		int a;
		scanf("%d", &a);
		cnt[a]++;
	}
	int countt = 0;
	for (int i = 0; i < MAX; i++){
		if (cnt[i]){
			if (i >= n){
				countt += cnt[i];
				continue;
			}
			cn.push_back(cnt[i]);
		}
	}
	dp[0][0] = 1LL;
	for (int i = 0; i < cn.size(); i++){
		for (int j = 0; j <= cn.size(); j++){
			dp[i + 1][j+1] += (dp[i][j]*cn[i])%MOD;
			dp[i + 1][j] += dp[i][j];
			dp[i + 1][j + 1] %= MOD;
			dp[i + 1][j] %= MOD;
		}
	}
	long long int ans = 0;
	for (int i = 0; i <= cn.size(); i++){
		long long int g = 1LL;
		if (i % 2 == 1LL){
			g = -1LL;
		}
		long long int way = dp[cn.size()][i] * k[n - i];// *ppow(k[n - i + countt - 1], MOD - 2);
		way %= MOD;
		if (g == -1){
			ans += MOD - way;
			ans %= MOD;
		}
		else{
			ans += way;
			ans %= MOD;
		}
	}
	//ans *= k[countt];
	//ans %= MOD;
	printf("%lld\n",ans);
	return 0;
	return 0;
}