#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N=510;
const ll mod=998244353;
ll c[N][N],dp[N][N],ans;int n,m,a[N],s[N];
int main()
{
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
		scanf("%d",&a[i]),s[i]=s[i-1]+a[i];
	for(int i=0;i<=s[n];i++)
		for(int j=0;j<=s[n];j++)
			c[i][j]=j==0?1:(c[i-1][j-1]+c[i-1][j])%mod;
	dp[0][0]=1;
	for(int i=0;i<n;i++)
		for(int j=0;j<=s[i];j++)
		{
			dp[i+1][j]=(dp[i+1][j]+dp[i][j])%mod;//加在最后
			for(int k=j+1;k<s[i+1];k++)
				for(int l=max(0,a[i+1]-(k-j));l<=min(a[i+1]-1,s[i+1]-k-1);l++)
					dp[i+1][k]=(dp[i+1][k]+dp[i][j]*c[k-j-1][a[i+1]-l-1])%mod; 
		}
	for(int i=0;i<s[n];i++)
		ans=(ans+dp[n][i])%mod;
	printf("%lld",ans);	
}