#include <bits/stdc++.h>
using namespace std;
bool is_prime(long long n) {
  if (n <= 1) {
    return false;
  }
  for (long long i = 2; i * i <= n; ++i) {
    if (n % i == 0) {
      return false;
    }
  }
  return true;
}
inline long long getPow(long long a, long long b) {
  long long res = 1ll, tp = a;
  while (b) {
    if (b & 1ll) {
      res *= tp;
    }
    tp *= tp;
    b >>= 1ll;
  }
  return res;
}
long long coso(long long x1, long long y1, long long x2, long long y2,
               long long x3, long long y3) {
  return abs((x2 - x1) * (y3 - y1) - (y2 - y1) * (x3 - x1));
}
inline long long nxt() {
  long long x;
  cin >> x;
  return x;
}
void ok() {
  puts("YES");
  exit(0);
}
void no() {
  puts("NO");
  exit(0);
}
const long long N = 1e6 + 5;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n;
  cin >> n;
  vector<long long> mas(n);
  for (int i = 0; i < n; i++) {
    cin >> mas[i];
  }
  vector<vector<long long>> dp(200 + 5, vector<long long>(2, 0LL));
  if (mas[0] == -1) {
    for (int i = 1; i <= 200; i++) {
      dp[i][1] = 1;
    }
  } else
    dp[mas[0]][1] = 1;
  for (int i = 1; i < n; i++) {
    long long cur = 0;
    vector<vector<long long>> dp2(200 + 5, vector<long long>(2, 0LL));
    for (int j = 1; j <= 200; j++) {
      dp2[j][1] = cur;
      cur = (cur + dp[j][0] + dp[j][1]);
      while (cur > 998244353) {
        cur -= 998244353;
      }
    }
    cur = 0;
    for (int j = 200; j >= 1; j--) {
      dp2[j][0] =
          ((dp2[j][0] + dp[j][0] + dp[j][1]) % 998244353 + cur) % 998244353;
      while (dp2[j][0] > 998244353) {
        dp2[j][0] -= 998244353;
      }
      cur = (cur + dp[j][0]);
      while (cur > 998244353) {
        cur -= 998244353;
      }
    }
    for (int j = 1; j <= 200; j++) {
      if (mas[i] != -1 && mas[i] != j) {
        dp2[j][0] = dp2[j][1] = 0;
      }
    }
    dp = dp2;
  }
  long long ans = 0LL;
  for (int i = 1; i <= 200; i++) {
    ans += dp[i][0];
  }
  cout << ans % 998244353;
  return 0;
}
