#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <numeric>
#include <cstring>
#include <queue>
#include <set>
#include <map>
#include <bitset>
#include <random>
#include <ctime>
#include <chrono>
#include <iomanip>

typedef long long ll;
typedef double lf;

// #define DEBUG 1
struct IO
{
    #define MAXSIZE (1 << 20)
    #define isdigit(x) (x >= '0' && x <= '9')
    char buf[MAXSIZE], *p1, *p2;
    char pbuf[MAXSIZE], *pp;
    #if DEBUG
    #else
    IO() : p1(buf), p2(buf), pp(pbuf) {}
    ~IO() {fwrite(pbuf, 1, pp - pbuf, stdout);}
    #endif
    #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
    #define blank(x) (x == ' ' || x == '\n' || x == '\r' || x == '\t')

    template <typename T>
    void Read(T &x)
    {
        #if DEBUG
        std::cin >> x;
        #else
        bool sign = 0; char ch = gc(); x = 0;
        for (; !isdigit(ch); ch = gc())
            if (ch == '-') sign = 1;
        for (; isdigit(ch); ch = gc()) x = x * 10 + (ch ^ 48);
        if (sign) x = -x;
        #endif
    }
    void Read(char *s)
    {
        #if DEBUG
        std::cin >> s;
        #else
        char ch = gc();
        for (; blank(ch); ch = gc());
        for (; !blank(ch); ch = gc()) *s++ = ch;
        *s = 0;
        #endif
    }
    void Read(char &c) {for (c = gc(); blank(c); c = gc());}

    void Push(const char &c)
    {
        #if DEBUG
        putchar(c);
        #else
        if (pp - pbuf == MAXSIZE) fwrite(pbuf, 1, MAXSIZE, stdout), pp = pbuf;
        *pp++ = c;
        #endif
    }
    template <typename T>
    void Write(T x)
    {
        if (x < 0) x = -x, Push('-');
        static T sta[35];
        int top = 0;
        do sta[top++] = x % 10, x /= 10; while (x);
        while (top) Push(sta[--top] ^ 48);
    }
    template <typename T>
    void Write(T x, char lst) {Write(x), Push(lst);}
} IO;
#define Read(x) IO.Read(x)
#define Write(x, y) IO.Write(x, y)
#define Put(x) IO.Push(x)

using namespace std;

const int MAXN = 5010, mod = 998244353;

inline void add(int &x, int y) { (x += y) >= mod && (x -= mod); }

int n, m, b[MAXN];

int f[2][MAXN], g[MAXN];

int id[MAXN], top;

int main()
{
    // freopen("preface.in", "r", stdin);
    // freopen("preface.out", "w", stdout);
    #if DEBUG
    #else
    ios::sync_with_stdio(0), cin.tie(0);
    #endif
    Read(n);
    for (int i = 1; i <= n; i++) Read(b[i]);
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= b[i]; j++) id[++top] = i;
    }
    // ll res = 0;
    // do
    // {
    //     // for (int i = 1; i <= top; i++) cout << id[i] << ' '; cout << "\n";
    //     int mn1 = 2e9, mn2 = 2e9; bool flag = 1;
    //     for (int i = top; i >= 1; i--)
    //     {
    //         if (id[i] > mn2) { flag = 0; break; }
    //         if (id[i] > mn1) mn2 = min(mn2, id[i]);
    //         mn1 = min(mn1, id[i]);
    //     }
    //     res += flag;
    // }while (next_permutation(id + 1, id + top + 1));
    // res %= mod;
    // cout << res % mod << '\n';
    int p = -1;
    for (int _ = 1; _ <= n; _++)
    {
        if (!b[_]) continue;
        if (p == -1) { f[p = 0][m = b[_]] = 1; continue; }
        for (int i = 0; i <= b[_] + m; i++) g[i] = 0;
        for (int i = 0; i <= m; i++) g[i + b[_]] = f[p][i];
        for (int i = 1; i <= b[_]; i++)
        {
            for (int j = 0; j <= m + 1; j++) f[p ^ 1][j] = 0;
            int sum = 0;
            for (int j = m; j >= 1; j--)
            {
                add(sum, f[p][j]);
                add(f[p ^ 1][j], sum);
            }
            m++, p ^= 1;
            if (i != b[_]) for (int j = 0; j <= m; j++) add(g[j + b[_] - i], f[p][j]);
            // cout << m << '\n';
            // for (int j = 0; j <= m; j++) cout << f[p][j] << ' '; cout << '\n';
            // for (int j = 0; j <= m + b[_] - i; j++) cout << g[j] << ' '; cout << '\n';
        }
        for (int j = 0; j <= m; j++) add(f[p][j], g[j]);
        // for (int i = 0; i <= m; i++) cout << f[p][i] << ' '; cout << '\n';
    }
    int ans = 0;
    for (int i = 0; i <= m; i++) add(ans, f[p][i]);
    // if (ans != res) cout << "WA\n";
    cout << ans << '\n';
    return 0;
}