#include<bits/stdc++.h>
using namespace std;
const int maxn = 105, mod = 998244353;
int n;
int a[maxn], s[maxn];
int dp[maxn][maxn][maxn];
int main() {
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i], s[i] = s[i - 1] + a[i];
    for (int i = 1; i <= n; i++)
        if (a[i]) dp[1][i][1] = 1;
    for (int i = 1; i < s[n]; i++)
        for (int j = 1; j <= n; j++)
            for (int k = 1; k <= a[j]; k++) {
                if (i != s[j]) dp[i + 1][j][k] = (dp[i + 1][j][k] + dp[i][j][k]) % mod;
                if (k != a[j]) dp[i + 1][j][k + 1] = (dp[i + 1][j][k + 1] + dp[i][j][k]) % mod;
                for (int x = j + 1; x <= n; x++) dp[i + 1][x][1] = (dp[i + 1][x][1] + dp[i][j][k]) % mod;
            }
    cout << dp[s[n]][n][a[n]] << '\n';
    return 0;
}