#include <algorithm>
#include <iostream>
#include <vector>

using namespace std;

constexpr long long M = 1e9+7;

int main(){
	int n; cin >> n;
	vector<long long> v(n), dp(n), f(n+1);
	for(auto &x:v) cin >> x;
	sort(v.begin(), v.end());
	f[0] = 1;
	for(int i = 0; i < n; ++i){
		dp[i] = f[i+1] = (i+1) * f[i] % M;
		for(int j = 0; j < i; ++j)
			dp[i] -= dp[j] * f[i-j] % M;
		dp[i] %= M;
	}
	cout << dp[n-1] << endl;
}