import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;

public class Main {
	final long MOD = 1_000_000_000 + 7;
	long[] fac = new long[10000];
	{
		fac[0] = 1;
		for (int i = 1; i < fac.length; ++i)
			fac[i] = fac[i - 1] * i % MOD;
	}

	void run() {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int[] A = new int[N];
		int[] cnt = new int[5000];
		for (int i = 0; i < N; ++i) {
			A[i] = sc.nextInt();
			++cnt[A[i]];
		}
		long[] f = new long[N + 1];
		f[0] = 1;
		for (int i = 0; i <= N - 1; ++i) {
			for (int j = N - 1; j >= 0; --j) {
				f[j + 1] += f[j] * cnt[i] % MOD;
				f[j + 1] %= MOD;
			}
		}
		long ans = 0;

		for (int i = 0; i <= N; ++i) {
			ans += fac[N - i] * f[i] % MOD * (i % 2 == 0 ? 1 : MOD - 1) % MOD;
			ans %= MOD;
		}
		System.out.println(ans);
	}

	public static void main(String[] args) {
		new Main().run();
	}

	void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}

}