#include <bits/stdc++.h>
using namespace std;

#define ll long long
typedef int uci;
#define int long long
#define F first
#define S second
#define ar array

const ll MOD = 998244353;
vector<ll> FACTS(1000);

ll modexp(ll n, ll p) {
    ll r = 1;
    ll m = n;
    while(p) {
        if(p&1) r = (r*m)%MOD;
        m = (m*m)%MOD;
        p >>= 1;
    }
    return r;
}

ll modinv(ll n) {
    return modexp(n, MOD-2);
}


ll NCK(ll n, ll k) {
    ll re = FACTS[n];
    re = (re*modinv(FACTS[k]))%MOD;
    re = (re*modinv(FACTS[n-k]))%MOD;
    return re;
}


void solve(){
    FACTS[0] = 1;
    for(ll i = 1; i < FACTS.size(); i++)
        FACTS[i] = FACTS[i-1]*i % MOD;

    vector<vector<ll>> NCKS(1001, vector<ll>(2001));
    for(ll i = 0; i < NCKS.size(); i++) {
        NCKS[i][0] = 1;
        for(ll j = 1; j <= i; j++) {
            NCKS[i][j] = (NCKS[i][j-1] + NCK(i, j)) % MOD;
        }
    }

    ll N; cin >> N;
    vector<ll> A(N);
    for(ll i = 0; i < N; i++) cin >> A[i];

    vector<vector<ll>> DP(1000, vector<ll>(2000));
    DP[0][0] = 1;
    for(ll a = 1; a <= N; a++) {
        for(ll nbp = 0; nbp <= 500; nbp++) {
            for(ll d = -nbp; d <= A[a-1]; d++) {
                ll max_placed = min(nbp, A[a-1] - 1 - d);

                if(d == A[a-1]) {
                    (DP[a][nbp + d] += DP[a-1][nbp]) %= MOD;
                } else {
                    ll mi_placed = max(0ll, -d);
                    ll m = NCKS[A[a-1]-d-1][max_placed];
                    if(mi_placed > 0) (m += MOD - NCKS[A[a-1]-d-1][mi_placed-1]) %= MOD;
                    (DP[a][nbp + d] += DP[a-1][nbp] * m) %= MOD;
                }

            }
        }
    }

    /*for(ll a = 1; a <= N; a++) {
        for(ll nbp = 0; nbp <= 500; nbp++) {
            if(DP[a][nbp] > 0)
                cout << a << " " << nbp << " " << DP[a][nbp] << endl;
        }
    }*/
    cout << DP[N][0] << endl;
}

uci main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    solve();
}