#include <bits/stdc++.h>
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define st first
#define nd second
using namespace std;
typedef long long ll;
const int mod = 1e9 + 7;
const int N = 1e3 + 5;
int fac[N], ifac[N], inv[N];
int dp[N][N];

void add(int& x, int y) {
	x += y;
	if (x >= mod)
		x -= mod;
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(0);
	fac[0] = ifac[0] = fac[1] = ifac[1] = inv[1] = 1;
	for (int i = 2; i < N; i++) {
		inv[i] = mod - (mod / i) * 1ll * inv[mod % i] % mod;
		fac[i] = fac[i - 1] * 1ll * i % mod;
		ifac[i] = ifac[i - 1] * 1ll * inv[i] % mod;
	}
	int n; cin >> n;
	vector<int> a(n);
	for (int i = 0; i < n; i++)
		cin >> a[i];
	dp[0][0] = 1;
	int s = 0;
	for (int i = 0; i < n; i++) if (a[i] != 0) {
		for (int x = s, y = 0; x >= y; x--, y++) {
			for (int j = a[i]; j >= 0 && x + j >= y + a[i] - j; j--) {
				if (y + a[i] - j <= x)
					add(dp[x + j][y + a[i] - j], dp[x][y]);
			}
		}
		s += a[i];
	}
	int ans = 0;
	for (int i = 0; 2 * i <= s; i++) {
		int val = dp[s - i][i];
		ans = (ans + val * 1ll * val) % mod;
	}
	cout << ans << "\n";
}