#include<bits/stdc++.h> #define int long long #define rep(i,a,b) for(register int i=(a);i<=(b);i++) #define per(i,a,b) for(register int i=(a);i>=(b);i--) using namespace std; const int mod=998244353; inline int read() { register int x=0, f=1; register char c=getchar(); while(c<'0'||c>'9') {if(c=='-') f=-1; c=getchar();} while(c>='0'&&c<='9') {x=(x<<3)+(x<<1)+c-48,c=getchar();} return x*f; }

signed main() { int n=read(),m=0,ans=1; rep(i,1,n) m+=read(); rep(i,2,m) ans=ans*(i==m-n+1?1:i)%mod; printf("%lld\n",ans); return 0; } //难得来 Hydro Online Judge