#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i, l, r) for (ll i = (l); i < (r); ++i)
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pl = pair<ll,ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using vvvl = vector<vector<vector<ll>>>;
template<class T> using pq_ = priority_queue<T, vector<T>, greater<T>>;
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
using mint=modint998244353;
// g++ a.cpp -std=c++23 -I.
// g++ -std=c++23 -I. a.cpp -o main
// g++ -std=c++23 -I. anaive.cpp -o naive
// g++ -std=c++23 -I. agene.cpp -o gene
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <boost/multiprecision/cpp_int.hpp>
namespace mp = boost::multiprecision;
using Bint = mp::cpp_int;
using Real = mp::number<mp::cpp_dec_float<1024>>;

mint solve(vl &a,vector<mint> &bik,vector<mint> &gbik){
    vl uc;
    ll nowc=0;
    rep(i,0,a.size()){
        if(a[i]==1)nowc++;
        else uc.push_back(nowc);
    }
    ll n=uc.size();
    ll m=nowc;
    ll d=0;
    ll e=-1;
    mint now=bik[n+m]*gbik[n]*gbik[m];
    mint nows=0;
    mint u=1;
    mint anss=0;
    mint ans=0;
    mint miniu=1;
    rep(i,0,n){
        //cout<<uc[i];
    }
   // cout<<endl;
    rep(i,0,n){
        while(d<uc[i]){
            anss+=now;
            if(i!=0)now+=bik[i-1+d+1]*gbik[i-1]*gbik[d+1]*bik[(n-1)-(i-1)+m-(d+1)]*gbik[(n-1)-(i-1)]*gbik[m-(d+1)];
            d++;
        }
        if(m-1-(d)>=0)now-=bik[i+d]*gbik[i]*gbik[d]*bik[n-i+(m-1-(d))]*gbik[n-i]*gbik[m-1-(d)];
        while(e<uc[i]-1){
            nows+=bik[i+e+1]*gbik[i]*gbik[e+1]*bik[(n)-(i)+(m-1)-(e+1)]*gbik[(n)-(i)]*gbik[(m-1)-(e+1)];
            e++;
        }
        anss-=nows;
        if(m-2-(e)>=0)nows-=bik[i+1+e]*gbik[i+1]*gbik[e]*bik[n+1-(i+1)+(m-2-(e))]*gbik[n+1-(i+1)]*gbik[(m-2-(e))];
        //cout<<anss.val()<<endl;
        ans+=anss;
    }
    //cout<<ans.val()<<endl;
    return ans;
}


int main(){
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    ll trc=710000;
    vector<mint> bik(trc+1);
    vector<mint> gbik(trc+1);
    bik[0]=1;
    rep(i,0,trc){
        bik[i+1]=bik[i]*(i+1);
    }
    gbik[trc]=1/bik[trc];
    rep(i,0,trc){
        gbik[trc-i-1]=gbik[trc-i]*(trc-i);
    }
    ll n;
    cin>>n;
    vl a;
    rep(i,0,n){
        ll k;
        cin>>k;
        rep(i,0,k)a.push_back(1);
        if(i!=n-1)a.push_back(0);
    }
    mint ans=0;
    ans+=solve(a,bik,gbik);
    rep(i,0,a.size()){
        a[i]=1-a[i];
    }
    ans+=solve(a,bik,gbik);
    cout<<ans.val()<<endl;
}