#include <map>
#include <set>
#include <array>
#include <cmath>
#include <deque>
#include <bitset>
#include <random>
#include <string>
#include <vector>
#include <cassert>
#include <complex>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#include <unordered_set>

using namespace std;

const int MOD = 998244353;

int add(int a, int b) {
  return a + b >= MOD ? a + b - MOD : a + b;
}

int sub(int a, int b) {
  return a >= b ? a - b : a + MOD - b;
}

int mul(int a, int b) {
  return (1ll * a * b) % MOD;
}

const int MAXN = 510;
int dp[MAXN][MAXN];
int C[MAXN][MAXN];
int pC[MAXN][MAXN];


int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);

  for (int n = 0; n < MAXN - 5; ++n) {
    C[n][0] = 1;
    pC[n][0] = 0;
    pC[n][1] = 1;
    for (int k = 1; k <= n; ++k) {
      C[n][k] = add(C[n - 1][k - 1], C[n - 1][k]);
      pC[n][k + 1] = add(pC[n][k], C[n][k]);
    }
  }

  int n;
  cin >> n;
  vector<int> c;
  for (int i = 0; i < n; ++i) {
    int val;
    cin >> val;
    if (val > 0) {
      c.push_back(val);
    }
  }
  n = c.size();
  int sum = c[0];
  dp[1][c[0]] = 1;
  for (int i = 1; i < n; ++i) {
    for (int d = 0; d <= sum; ++d) {
      dp[i + 1][d + c[i]] = add(dp[i + 1][d + c[i]], dp[i][d]);
      for (int delta = 1 - c[i]; delta <= d - 1; ++delta) {
        int lx = 1, rx = c[i];
        lx = max(lx, 1 - delta);
        rx = min(rx, d - delta);
        int sum = sub(pC[d - 1 - delta][rx], pC[d - 1 - delta][lx - 1]);
        dp[i + 1][c[i] + delta] = add(dp[i + 1][c[i] + delta], mul(sum, dp[i][d]));
      }
    }
    sum += c[i];
  }
  int ans = 0;
  for (int d = 0; d <= sum; ++d) {
    ans = add(ans, dp[n][d]);
  }
  cout << ans << "\n";
  return 0;
}