#include <fstream>
#define N 1010
#define M 2010
typedef long long ll;
using namespace std;
int n,m=0;
int num[N]={0};
ll sum[N]={0};
ll C[M][M]={0};
//ll f[N][M][2]={0};
ll mod=998244353;
ifstream in("asm_formation.in");
ofstream out("asm_formation.out");
void read()
{
	int i,j;
	in>>n;
	for(i=1;i<=n;i++)in>>num[i];
	for(i=1;i<=n;i++)sum[i]=sum[i-1]+num[i];
	for(i=1;i<=M-3;i++)
	{
		C[i][1]=1;
		C[1][i]=i;
		C[0][i]=1;
	}
	for(i=2;i<=M-3;i++)
	{
		for(j=2;j<=M-3;j++)
		{
			C[i][j]=(C[i-1][j]+C[i][j-1])%mod;
		}
	}
}
void work()
{
	int i,x,y;
	ll ans=1;
	//for(i=1;i<=n;i++)out<<sum[i]<<' ';
	for(i=2;i<=n;i++)
	{
		x=sum[i-1]+num[i]-1;
		y=num[i]-1;
		//out<<x<<' '<<y<<endl;
		ans*=C[y][x];
		ans%=mod;
	}
	out<<ans<<endl;
}
int main()
{
	read();
	work();
	return 0;
}