#include<bits/stdc++.h>
using namespace std;
#define int long long
const int mod = 1e9 + 7;
int n, m, a[110], ans;
void dfs(int x, int lst) {
	if(x == n + 1) {
		ans ++;
		if(ans >= mod) {
			ans -= mod;
		}
		return ;
	}
	for(int i = 1; i <= m; i ++) {
		if(a[i] && i != lst) {
			a[i] --;
			dfs(x + 1, i);
			a[i] ++;
		}
	}
}
signed main() {
	freopen("color.in", "r", stdin);
	freopen("color.out", "w", stdout);
	cin >> m;
	for(int i = 1; i <= m; i ++) {
		cin >> a[i];
		n += a[i];
	}
	dfs(1, 0);
	cout << ans;
	return 0;
}