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

const int N = 510, P = 998244353;

int c[N][N];

int main() {
    for(int i = 0; i < N; i ++) {
        c[i][0] = 1;
        for(int j = 1; j <= i; j ++)
            c[i][j] = (c[i - 1][j] + c[i - 1][j - 1]) % P;
    }
    int n, len = 0, sum = 0;
    cin >> n;
    vector<int> a(n);
    for(int i = 0; i < n; i ++)
        cin >> a[i];
    len = accumulate(a.begin(), a.end(), 0);
    vector<int> dp(n + 1, 0);
    for(int i = 1; i <= n; i ++)
        dp[i] = (P + c[i][a[0]] - c[i - 1][a[0]]) % P;
    
    sum = a[0];
    for(int i = 1; i < n; i ++) {
        vector<int> tmp(n + 1, 0);
        for(int j = 1; j <= n; j ++) {
            for(int k = 0, uk = min(j - sum, a[i]); k <= uk; k ++)
                for(int l = j; l <= n; l ++)
                    tmp[l] = (tmp[l] + dp[j] * (long long)(P + c[l - j][a[i] - k] - (l > j ? c[l - j - 1][a[i] - k] : 0))) % P; 
        }
        swap(tmp, dp);
        sum += a[i];
    }
    cout << dp[n];
}