#include <bits/stdc++.h>
using namespace std;
const int mod = 998244353;
const int N = 510;
int n, m, C[N][N];
int a[N];
int f[N], g[N];

int main() {
	ios::sync_with_stdio(0); cin.tie(nullptr);
	C[0][0] = 1;
	for(int i = 1; i <= 500; i++) {
		C[i][0] = 1;
		for(int j = 1; j <= i; j++) C[i][j] = (C[i - 1][j] + C[i - 1][j - 1]) % mod;
	}
	cin >> n;
	for(int i = 1; i <= n; i++) cin >> a[i];
	for(int i = 2; i <= n; i++) a[i] += a[i - 1];
	m = a[n];
	f[0] = 1;
	for(int i = 1; i <= n; i++) {
		int c = a[i] - a[i - 1];
		if(!c) continue;
		for(int j = 0; j <= m; j++) g[j] = 0;
		for(int j = 0; j <= a[i - 1]; j++) {
			if(f[j] == 0) continue;
			g[j] = (g[j] + f[j]) % mod;
			for(int k = 0; k <= a[i - 1] - j; k++)
				for(int h = 1; h <= c; h++) {
					g[j + k + h] = (g[j + k + h] + 1ll * f[j] * C[k + h - 1][k] % mod) % mod;
				}
		}
		swap(f, g);
		// cout << ">>> ";
		// for(int j = 0; j <= m; j++) cout << f[j] << " ";
		// cout << "\n";
	}
	cout << f[m] << "\n";
	return 0;
}