#include <stdio.h>

long long power_mod (long long a, long long b, long long mod_num) {
  long long ans = 1LL;
  
  if (b > 0LL) {
    ans = power_mod(a, b/2LL, mod_num);
    ans = (ans * ans) % mod_num;
    if (b%2LL == 1LL) {
      ans = (ans * a) % mod_num;
    }
  }
  
  return ans;
}

int main () {
  int n = 0;
  int a[200000] = {};
  
  int res = 0;
  
  long long ans = 0LL;
  long long mod_num = 998244353LL;
  
  int btotal = 0;
  int bcnt = 0;
  int max = 0;
  
  long long fact[200001] = {};
  long long invf[200001] = {};
  
  int cnt[200001] = {};
  
  res = scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    res = scanf("%d", a+i);
    if (a[i] < 0) {
      btotal++;
    } else {
      cnt[a[i]] = 1;
    }
  }
  
  fact[0] = 1LL;
  for (int i = 0; i < n; i++) {
    fact[i+1] = fact[i];
    fact[i+1] *= (long long)(i+1);
    fact[i+1] %= mod_num;
  }
  
  invf[n] = power_mod(fact[n], mod_num-2LL, mod_num);
  for (int i = n; i > 0; i--) {
    invf[i-1] = invf[i];
    invf[i-1] *= (long long)i;
    invf[i-1] %= mod_num;
  }
  
  for (int i = 0; i < n; i++) {
    cnt[i+1] += cnt[i];
  }
  
  for (int i = 0; i < n; i++) {
    if (a[i] < 0) {
      long long tmp = fact[btotal];
      tmp *= invf[bcnt+1];
      tmp %= mod_num;
      tmp *= fact[bcnt];
      ans += tmp;
      ans %= mod_num;
      if (max-cnt[max] > bcnt) {
        long long tmp = fact[max-cnt[max]];
        tmp *= invf[bcnt+1];
        tmp %= mod_num;
        tmp *= invf[max-cnt[max]-bcnt-1];
        tmp %= mod_num;
        tmp *= fact[bcnt];
        tmp %= mod_num;
        tmp *= fact[btotal-bcnt-1];
        ans += mod_num-tmp%mod_num;
        ans %= mod_num;
      }
      bcnt++;
    } else if (a[i] > max) {
      if (a[i]-cnt[a[i]] >= bcnt) {
        long long tmp = fact[a[i]-cnt[a[i]]];
        tmp %= mod_num;
        tmp *= invf[a[i]-cnt[a[i]]-bcnt];
        tmp %= mod_num;
        tmp *= fact[btotal-bcnt];
        ans += tmp;
        ans %= mod_num;
      }
      max = a[i];
    }
  }
  
  printf("%lld\n", ans);
  return 0;
}