#include <bits/stdc++.h>
using namespace std;
#define sz(x) (long long) (x).size()
#define all(x) (x).begin(), (x).end()
#define show(x) cerr << #x << " is " << x << endl;
#define show2(x,y) cerr << #x << " is " << x << " " << #y << " is " << y << endl;
#define show3(x,y,z) cerr << #x << " is " << x << " " << #y << " is " << y << " " << #z << " is " << z << endl;
#define int long long
typedef pair<int,int> ii;

int n;

int dp[505][505]; ///i, last length
int choose[1005][1005];
int mod = 998244353;
signed main(){
	ios_base::sync_with_stdio(false); cin.tie(0);
	
	choose[0][0] = 1;
	for(int a = 1;a <= 1000;a++){
		for(int b = 0;b <= a;b++){
			choose[a][b] = (choose[a-1][b] + choose[a-1][b-1]) % mod;
		}
	}
	
	cin >> n;
	int t = 0;
	for(int i = 1;i <= n;i++){
		int a; cin >> a;
		if(i == 1){
			dp[i][0] = 1;
			t = a;
			continue;
		}
		
		if(a == 1){
			int csum = 0;
			///insert in the middle
			for(int r = 0;r < t;r++){
				csum += dp[i-1][r];
				csum %= mod;
				
				dp[i][r+1] += csum;
				dp[i][r+1] %= mod;
			}
			
			///insert in the end
			for(int r = 0;r <= t;r++){
				dp[i][r] += dp[i-1][r];
				dp[i][r] %= mod;
			}
		}
		else{
			///insert in the middle
			int csum = 0;
			for(int l = 0;l <= t;l++){
				csum += dp[i-1][l];
				csum %= mod;
				for(int r = l+1;r <= t;r++){
					
					int between = r-l-1;
					int toadd = a - 2;
					
					dp[i][r+a] += csum * choose[between+toadd][toadd];
					dp[i][r+a] %= mod;
				}
				
				///it extends to the end
				for(int e = 1;e < a;e++){
					int mid = a - e;
					dp[i][t+mid] += csum*choose[mid+t-l-1][mid];
					dp[i][t+mid] %= mod;
				}
			}
			
			///insert all in the end
			for(int r = 0;r <= t;r++){
				dp[i][r] += dp[i-1][r];
				dp[i][r] %= mod;
			}
		}
		t += a;
	}
	
	for(int i = 1;i <= n;i++) for(int j = 0;j <= t;j++) show3(i, j, dp[i][j]);
	
	int ans = 0;
	for(int i = 0;i <= 504;i++){
		ans += dp[n][i]; ans %= mod;
	}
	
	cout << ans;
}