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

#define pb push_back
#define Mp make_pair
#define SZ(x) (int((x).size()))

typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

const int MAXN = 505, Mod = 998244353;

int n;
int a[MAXN];
int f[MAXN][MAXN];
int C[MAXN][MAXN];
inline int Binom(int n, int m) {
    if(n < 0 || m < 0 || n < m) return 0;
    return C[n][m];    
}

void solve() {
    for(int i = 0; i <= 500; i++) {
        C[i][0] = 1;
        for(int j = 1; j <= i; j++) {
            C[i][j] = (C[i - 1][j - 1] + C[i - 1][j]) % Mod;
        }
    }
    cin >> n;
    for(int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    f[n + 1][0] = 1;
    for(int i = n; i >= 1; i--) {
        for(int j = 0; j <= n; j++) if(f[i + 1][j]) {
            for(int t = 0; t < a[i]; t++) {
                for(int k = 1; k <= j; k++) {
                    f[i][k + t] = (f[i][k + t] + 1ll * f[i + 1][j] * Binom(a[i] - t - 1 + (j - k), j - k)) % Mod;
                }
            } 
            f[i][j + a[i]] = (f[i][j + a[i]] + f[i + 1][j]) % Mod;
        }
    }
    int ans = 0;
    for(int i = 0; i <= n; i++) ans = (ans + f[1][i]) % Mod;
    cout << ans << '\n';
}
signed main() {
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    int t = 1;
    while(t--) solve();
    return 0;
}