#include <cstdio>
using ll = long long int;
const ll MOD = 998244353;
ll dp[2010][2010], sum[2010][2010];
int main() {
    int N; scanf("%d", &N);
    dp[0][0] = 1;
    for(int i=0; i<N; i++) {
        ll V; scanf("%lld", &V);
        for(int j=0; j<=N; j++) {
            // 使わない
            (dp[i+1][j] += dp[i][j]) %= MOD;
            (sum[i+1][j] += sum[i][j]) %= MOD;
            // 使う
            (dp[i+1][j+1] += dp[i][j]) %= MOD;
            (sum[i+1][j+1] += sum[i][j]) %= MOD;
            (sum[i+1][j+1] += (j+1) * V % MOD * dp[i][j]) %= MOD;
        }
    }

    ll ans = 0;
    for(int i=0; i<=N; i++) (ans += sum[N][i]) %= MOD;
    printf("%lld\n", ans);
    return 0;
}