//Author: Kevin
#include<bits/stdc++.h>
//#pragma GCC optimize("O2")
using namespace std;
#define ll long long
#define ull unsigned ll
#define pb emplace_back
#define mp make_pair
#define ALL(x) (x).begin(),(x).end()
#define rALL(x) (x).rbegin(),(x).rend()
#define srt(x) sort(ALL(x))
#define rev(x) reverse(ALL(x))
#define rsrt(x) sort(rALL(x))
#define sz(x) (int)(x.size())
#define inf 0x3f3f3f3f
#define pii pair<int,int>
#define lb(v,x) (int)(lower_bound(ALL(v),x)-v.begin())
#define ub(v,x) (int)(upper_bound(ALL(v),x)-v.begin())
#define uni(v) v.resize(unique(ALL(v))-v.begin())
#define longer __int128_t
void die(string S){puts(S.c_str());exit(0);}
const ll mod=998244353;
int a[505];
int f[505];
int g[505];
ll C[1010][1010];
ll func(int x,int y)
{
	if(!x) return (y==0);
	return C[x+y-1][x-1];
}
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	for(int i=0;i<1010;i++)
		C[i][0]=C[i][i]=1;
	for(int i=2;i<1010;i++)
		for(int j=1;j<i;j++)
			C[i][j]=(C[i-1][j]+C[i-1][j-1])%mod;
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
		cin>>a[i];
	int s=0;
	f[0]=1;
	for(int i=1;i<=n;i++) if(a[i])
	{
		if(!s)
		{
			s+=a[i];
			f[0]=0;
			f[s+1]=1;
			continue;
		}
		memset(g,0,sizeof(g));
		for(int c=0;c<a[i];c++)
			for(int j=1;j<=s+1;j++)
				for(int k=1;k<j;k++)
				{
					ll ways=(func(j-k+1,a[i]-c)-func(j-k,a[i]-c)+mod)%mod;
					g[c+k+1]=(g[c+k+1]+f[j]*ways)%mod;
				}
		for(int j=1;j<=s+1;j++)
			g[a[i]+j]=(g[a[i]+j]+f[j])%mod;
		memcpy(f,g,sizeof(g));
		s+=a[i];
//		for(int i=1;i<=s+1;i++)
//			cout<<f[i]<<" ";
//		cout<<endl;
	}
	ll ans=0;
	for(int i=1;i<=s+1;i++)
		ans=(ans+f[i])%mod;
	cout<<ans<<endl;
	return 0;
}