#include<bits/stdc++.h>
#define MAXN 100010
#define MOD 998244353
#define LL long long
using namespace std;
int K,num[MAXN];
LL fac[500010],inv[500010];//fac[i]表示i的阶乘，inv[i]表示i的阶乘的逆元 
LL Quick_Pow(LL a,LL b){
	LL x=1;
	while(b){
		if(b&1)x=(x*a)%MOD;
		a=(a*a)%MOD;
		b>>=1;
	}
	return x;
}
void Inverse(){
	fac[0]=1;
	for(int i=1;i<=num[K];i++)fac[i]=(fac[i-1]*i)%MOD; 
	inv[num[K]]=Quick_Pow(fac[num[K]],MOD-2);
	for(int i=num[K]-1;i>=0;i--){inv[i]=(inv[i+1]*(i+1))%MOD;}
}
int main(){
	freopen("asm_formation.in","r",stdin);
	freopen("asm_formation.out","w",stdout);
	LL ans=1;
	scanf("%d",&K);
	for(int i=1;i<=K;i++){scanf("%d",&num[i]);num[i]+=num[i-1];}
	Inverse(); 
	for(int i=2;i<=K;i++){
		ans=(ans*fac[num[i]-1])%MOD;
		ans=(ans*inv[num[i-1]])%MOD;
		ans=(ans*inv[num[i]-1-num[i-1]])%MOD;
	}
	printf("%lld",ans);
	return 0;
}