# include <bits/stdc++.h>
using namespace std;
mt19937 rnd(time(0));
using i64 = long long;
const int N = 505; 
const i64 mod = 998244353; 
int n, a[N]; 
i64 dp[N][N], fac[N], ifac[N]; 
void Add(i64 &x, i64 y) { x = (x + y) % mod; if(x < 0) x += mod; return; }
i64 qpow(i64 x, i64 p = mod - 2ll)
{
	i64 ans = 1ll;
	while(p)
	{
		if(p & 1) ans = ans * x % mod;
		x = x * x % mod, p >>= 1;
	}
	return ans;
}
i64 C(i64 n, i64 m)
{
	return fac[n] * ifac[m] % mod * ifac[n - m] % mod;
}
int main(void)
{
	fac[0] = 1ll; 
	for(int i = 1; i <= N - 5; i++) fac[i] = fac[i - 1] * i % mod; 
	ifac[N - 5] = qpow(fac[N - 5]);
	for(int i = N - 6; i >= 0; i--) ifac[i] = ifac[i + 1] * (i + 1) % mod;
	scanf("%d", &n); 
	for(int i = n; i >= 1; i--) scanf("%d", &a[i]); 
	dp[0][0] = 1; 
	dp[1][a[1] + 1] = 1; 
	int suma = 0; 
	for(int i = 2; i <= n; i++)
	{
		suma += a[i - 1]; 
		for(int j = 1; j <= suma + 1; j++)
		{
			for(int k = 0; k < a[i]; k++)
			{
				for(int l = 1; l < j; l++)
				{
					Add(dp[i][l + k + 1], dp[i - 1][j] * C(j - l - 1 + a[i] - k - 1, j - l - 1) % mod);
				}
			}
			Add(dp[i][j + a[i]], dp[i - 1][j]);
			// printf("dp[%d][%d] = %lld\n", i, j, dp[i][j]);
		}
	}
	suma += a[n]; 
	i64 sum = 0;
	for(int i = 1; i <= suma + 1; i++) Add(sum, dp[n][i]); 
	printf("%lld\n", sum);
	return 0; 
}