#include <iostream>
#include <cstring>
using namespace std;
const int N = 501, p = 998244353;

void addmod(int &x, int y) {
    x += y;
    if(x >= p)
        x -= p;
}

int n, m, a[N], nxt[N];

int dp[2][N][2], (*f)[2] = dp[0], (*g)[2] = dp[1];
const int SZ = sizeof(int) * N * 2;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n;
    int p = 0;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        m += a[i];
        while(p < m)
            nxt[p++] = m;
    }
    g[0][0] = 1;
    for (int i = 0; i < m; i++) {
        swap(f, g);
        memset(g, 0, SZ);
        for (int j = i; j <= m; j++) {
            addmod(g[j][0], f[j][0]);
            for (int k = 0; k <= 1; k++) {
                if(j < m)
                    addmod(g[j + 1][0], f[j][k]);
                if(nxt[j] > j)
                    addmod(f[nxt[j]][1], f[j][k]);
            }
        }
    }
    cout << g[m][0];
    return 0;
}