#include<bits/stdc++.h>
#define int long long
using namespace std;
int n,m, a[1010], f[510][510], cnt = 1;
int mod = 998244353, c[510][510];
signed main() {
	cin>>n;
	for(int i = 1;i <= n;i ++)
	{
		cin>>a[cnt];
		m += a[cnt];
		if(a[cnt])cnt ++;
	}
	c[0][0] = 1;
	for(int i = 1;i <= m;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;
			//cout<<i<<' '<<j<<' '<<c[i][j]<<endl;
		}
	}
	cnt -= 1;
	f[1][0] = 1;
	int tot = 0;
	//for(int i = 1;i <= cnt;i ++)cout<<a[i]<<' ';
	for(int i = 1;i < cnt;i ++)
	{
		f[i][0] = 1;
		tot += a[i];
		for(int j = 0;j <= m;j ++)
		{
			for(int k = 0;k <= tot;k ++)
			{
				for(int x = 0;x < a[i + 1];x ++)
				{
					if(j == 0)
					{
						f[i + 1][x + k + 1] = (f[i + 1][x + k + 1] + f[i][j]) % mod;
						continue;
					}
					int w = a[i + 1] - x - 1;
					if(j - k - 1 + w < 0)continue;
					f[i + 1][x + k + 1] = (f[i + 1][x + k + 1] + f[i][j] * c[j - k - 1 + w][w] % mod) % mod;
					//cout<<i<<' '<<j<<' '<<x+j+1<<' '<<w<<f[i +1][x + k +1]<<endl;
				}
			}
		}
	}
	int ans = 0;
	for(int i = 0;i <= m;i ++)ans = (ans + f[cnt][i]) % mod;
	cout<<ans % mod;
	return 0;
}