#include <bits/stdc++.h>

#define x first
#define y second
#define el '\n'
#define debug(x) cout << #x << ": " << x << endl
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int N = 3e5 + 10, INF = 0x3f3f3f3f, mod = 998244353;

void inc(ll &a, ll b) {
    a += b;
    if (a >= mod) a -= mod;
}
void dec(ll &a, ll b) {
    a -= b;
    if (a < 0) a += mod;
}
ll add(ll a, ll b) {
    a += b;
    return a >= mod ? a - mod : a;
}
ll del(ll a, ll b) {
    a -= b;
    return a < 0 ? a + mod : a;
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0);
    int n; cin >> n;
    vector<int> a(n + 1);
    for (int i = 1; i <= n; ++i) cin >> a[i];
    int m = accumulate(a.begin(), a.end(), 0);
    vector<vector<ll>> binom(m + 1, vector<ll>(m + 1)), sbinom(m + 1, vector<ll>(m + 1));
    for (int i = 0; i <= m; ++i) {
        for (int j = 0; j <= i; ++j) {
            if (!j) binom[i][j] = sbinom[i][j] = 1;
            else {
                binom[i][j] = add(binom[i - 1][j], binom[i - 1][j - 1]);
                sbinom[i][j] = add(sbinom[i][j - 1], binom[i][j]);
            }
        }
    }
    vector<ll> f;
    for (int i = 1, s = 0; i <= n; ++i) {
        if (!a[i]) continue;
        vector<ll> dp(s + a[i] + 1);
        for (int j = 1; j < a[i]; ++j) {
            inc(dp[j], sbinom[j - 1][j - 1]);
            if (j - s > 0) dec(dp[j], sbinom[j - 1][j - s - 1]);
        }
        for (int j = a[i]; j < s + a[i]; ++j) {
            inc(dp[j], sbinom[j - 1][a[i] - 1]);
            if (j - s > 0) dec(dp[j], sbinom[j - 1][j - s - 1]);
        }
        for (int j = 1; j <= s; ++j) {
            for (int k = j + 1; k < j + a[i]; ++k) {
                inc(dp[k], f[j] * sbinom[k - j - 1][k - j - 1] % mod);
                if (k - s > 0) dec(dp[k], f[j] * sbinom[k - j - 1][k - s - 1] % mod);
            }
            for (int k = j + a[i]; k < s + a[i]; ++k) {
                inc(dp[k], f[j] * sbinom[k - j - 1][a[i] - 1] % mod);
                if (k - s > 0) dec(dp[k], f[j] * sbinom[k - j - 1][k - s - 1] % mod);
            }
            // dec(dp[s + a[i]], f[j]);
            inc(dp[j], f[j]);
        }
        s += a[i];
        f.swap(dp);
        // for (int i: f) cout << i << ' '; cout << el;
    }
    ll ans = 1;
    for (ll i: f) inc(ans, i);
    cout << ans << el;
}