#include<bits/stdc++.h>

using namespace std;

const int N = 2e5 + 5, mod = 998244353;

int g[N], f[N], inv[N], n, a[N], vis[N], maxx, cnt, ans, s[N];

int A(int n, int m){
  if(m > n)return 0;
  return 1ll * f[n] * g[n - m] % mod;
}

int main(){
  inv[1] = f[0] = g[0] = 1;
  for(int i = 1; i <= 200000; ++i){
    f[i] = 1ll * f[i - 1] * i % mod;
    if(i > 1){
      inv[i] = 1ll * inv[mod % i] * (mod - mod / i) % mod;
    }
    g[i] = 1ll * g[i - 1] * inv[i] % mod;
  }
  cin >> n;
  for(int i = 1; i <= n; ++i){
    cin >> a[i];
    if(a[i] > 0){
      vis[a[i]] = 1;
    }
  }
  for(int i = 1; i <= n; ++i){
    s[i] = s[i - 1] + !vis[i];
  }
  maxx = 0;
  for(int i = 1; i <= n; ++i){
    maxx = max(maxx, a[i]);
    cnt += (a[i] == -1);
    if(a[i] > 0){
      if(maxx == a[i]){
        ans = (ans + 1ll * A(s[a[i]], cnt) * f[s[n] - cnt] % mod) % mod;
      }
    }
    else{
      ans = (ans + 1ll * (A(s[n], cnt) - A(s[maxx], cnt) + mod) % mod * f[s[n] - cnt] % mod * inv[cnt] % mod) % mod;
    }
  }
  cout << ans;
  return 0;
}