#include <cstdio>
#include <cstring>

using namespace std;

const int MOD = 998244353;
const int N = 505;
const int M = 1e3 + 50;

inline int add(int A, int B) {
	if(A + B >= MOD) return A + B - MOD;
	return A + B;
}

inline int sub(int A, int B) {
	if(A - B < 0) return A - B + MOD;
	return A - B;
}

inline int mul(int A, int B) {
	return (long long)A * B % MOD;
}

int ch[M][M], n, a[N], dp[N][N];

void precompute(){
	ch[0][0] = 1;
	for(int i = 1;i < M;i++) {
		ch[i][0] = 1, ch[i][i] = 1;
		for(int j = 1;j < i;j++)
			ch[i][j] = add(ch[i - 1][j - 1], ch[i - 1][j]);
	}
}

int f(int i, int zad) {
	if(i == n) return 1;
	if(dp[i][zad] != -1) return dp[i][zad];
	int ret = f(i + 1, zad + a[i]);
	if(a[i]) {
		for(int krj = 0;krj < a[i];krj++) {
			for(int nzad = 1;nzad <= zad;nzad++) {
				ret = add(ret, mul(f(i + 1, nzad + krj), ch[zad - nzad + a[i] - krj - 1][a[i] - krj - 1]));
			}
		}
	}
	return dp[i][zad] = ret;
}

int main(){
	memset(dp, -1, sizeof(dp));
	precompute();
	scanf("%d", &n);	
	for(int i = 0;i < n;i++) scanf("%d", a + i);
	printf("%d\n", f(1, a[0]));
	return 0;
}