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

#define C const
#define U unsigned
#define SC static
#define CE constexpr
#define TL template
#define TN typename
#define OP operator
#define pb push_back
#define ft first
#define sd second
#define mi (l + (r - l) / 2)
#define TTT TL<TN T = I>
#define BE(v) v.begin(), v.end()
#define VD void
#define I int
#define LL long long
#define STR string
using PII = pair<I, I>;
TTT using V = vector<T>;

#define FORX(v) for(auto& x : v)
#define FOR(i, b, e)  for(auto i = b, _e = (decltype(i))e; i != _e; ++i)
#define FORR(i, b, e) for(auto i = b, _e = (decltype(i))e; i != _e; --i)
#define FORV(v, i) for (I i = 0, _n = v.size(), x = _n ? v[0] : 0;i < _n;x = v[++i])
#define FORI(i, b, e) for(I i = b, _e = e; i <= _e; ++i)
#define FUNC(T, f, ...) function<T(__VA_ARGS__)> f = [&](__VA_ARGS__)->T

TTT CE T inf() { return numeric_limits<T>::max() / 2; }
TTT VD setmin(T& a, C T& b) { if (b < a)a = b; }
TTT VD setmax(T& a, C T& b) { if (a < b)a = b; }
TTT VD fastpow(T& a, T b, LL i) { for (;i;i >>= 1, b *= b)if (i & 1)a *= b; }

#define OPD(T,S,op,...) \
T& OP op##= (C S& _){{__VA_ARGS__} return *this;}\
friend T OP op (C T& a, C S& b) {T c = a; return c op##= b;}
#define OPB(T,op,...) friend bool OP op (C T& a, C T& b) {return __VA_ARGS__;}
#define OST(T) friend ostream& OP << (ostream & os, C T & a) { return os << a.x; }
struct Mod//WARNING : Mod MUST BE assigned in [0,m) unless using cc
{
	SC U I m; SC U LL i;
	SC VD set(U I mod) { m = mod, i = (U LL)(-1) / m + 1; }
	SC U I mul(U I a, U I b)
	{
		U LL x = (U LL)a * b, y = ((U __int128)x * i >> 64) * m;
		return x - y + (x < y ? m : 0);
	}
	U I x; CE Mod() :x(0) {}
	TTT CE Mod(T x) : x(x) {}
	TTT CE SC Mod cc(T x) { return (x % m + m) % m; }
	OPD(Mod, Mod, +, if ((x += _.x) >= m)x -= m;);
	OPD(Mod, Mod, -, if ((x += m - _.x) >= m)x -= m;);
	OPD(Mod, Mod, *, x = mul(x, _.x););
	OPD(Mod, Mod, / , fastpow(*this, _, m - 2););//m must be a prime
	OPD(Mod, I, ^, fastpow(*this, *this, _ - 1 + (_ > 0 ? 0 : m - 1)););
	OPB(Mod, == , a.x == b.x);
	OPB(Mod, != , a.x != b.x);
	OST(Mod)
};
U I Mod::m; U LL Mod::i;


VD test()
{
	Mod::set(998244353);
	I n, m = 0; cin >> n;
	V<I> a(n + 1); FORI(i, 1, n)cin >> a[i], m += a[i];
	V<V<Mod>> f(n + 1, V<Mod>(m + 1)); f[n][0] = 1;


	V<V<Mod>> c(m + 2, V<Mod>(m + 2)), sc(c);

	FORI(i, 0, m)
	{
		c[i][0] = c[i][i] = 1;
		FORI(j, 1, i - 1)c[i][j] = c[i - 1][j - 1] + c[i - 1][j];
		FORI(j, 1, m + 1)sc[i][j] = sc[i][j - 1] + c[i][j - 1];
	}

	FUNC(Mod, calc, I i, I j, I k)
	{
		if (i == 0 || j == 0)return k == 0;
		if (k > i + j || k < 2)return 0;
		return sc[i + j - k][j] - sc[i + j - k][j - 1 - min(k - 2, j - 1)];
	};

	I cnt = a[n];
	FORR(i, n - 1, 0)
	{
		f[i][0] = 1;

		FORI(j, 2, cnt + a[i])
		{
			f[i][j] += f[i + 1][0] * calc(cnt, a[i], j);
			FORI(k, 2, cnt)f[i][j] += f[i + 1][k] * calc(k - 1, a[i], j);
			if (j - a[i] > 1)f[i][j] += f[i + 1][j - a[i]];
		}
		cnt += a[i];
	}

	Mod ans;
	FORX(f[1])ans += x;
	cout << ans << '\n';
}

I main()
{
	ios::sync_with_stdio(0);
	cin.tie(0), cout.tie(0);
	if (fopen("test.in", "r"))
	{
		freopen("test.in", "r", stdin);
		freopen("test.out", "w", stdout);
	}
	I t = 1;
	// cin >> t;
	while (t--)test();
	return 0;
}