#include<bits/stdc++.h>
using namespace std;

//* ATCODER
#include<atcoder/all>
using namespace atcoder;
typedef modint998244353 mint;
//*/

/* BOOST MULTIPRECISION
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
//*/

typedef long long ll;

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)

template <typename T> bool chmin(T &a, const T &b) {
	if (a <= b) return false;
	a = b;
	return true;
}

template <typename T> bool chmax(T &a, const T &b) {
	if (a >= b) return false;
	a = b;
	return true;
}

template <typename T> T max(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmax(ret, a[i]);
	return ret;
}

template <typename T> T min(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmin(ret, a[i]);
	return ret;
}

template <typename T> T sum(vector<T> &a){
	T ret = 0;
	for (int i=0; i<(int)a.size(); i++) ret += a[i];
	return ret;
}

//defmodfact
const int COMinitMAX = 998244;
mint fact[COMinitMAX+1], factinv[COMinitMAX+1];

void modfact(){
	fact[0] = 1;
	for (int i=1; i<=COMinitMAX; i++){
		fact[i] = fact[i-1] * i;
	}
	factinv[COMinitMAX] = fact[COMinitMAX].inv();
	for (int i=COMinitMAX-1; i>=0; i--){
		factinv[i] = factinv[i+1] * (i+1);
	}
}

mint binom(int a, int b){
	if (a<b || b<0) return mint(0);
	return fact[a]*factinv[b]*factinv[a-b];
}
//--------


int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	modfact();

	int n; cin >> n;
	vector<int> a(n);
	int all_empty = 0;
	rep(i,0,n){
		cin >> a[i];
		a[i]--;
		all_empty += (a[i] < 0);
	}

	fenwick_tree<int> fw(n);
	rep(i,0,n){
		if (a[i] >= 0){
			fw.add(a[i],1);
		}
	}

	int now_empty = 0;
	mint ans = 0;
	int nowmax = -1;
	rep(i,0,n){
		if (a[i] < 0) {
			ans += fact[now_empty] * fact[all_empty - now_empty - 1] * 
			(
				binom(all_empty, now_empty+1)
				- binom(nowmax+1 - fw.sum(0, nowmax+1), now_empty+1)
			);
			now_empty++;
		}else{
			int freedom = a[i] - fw.sum(0, a[i]);
			if (chmax(nowmax, a[i])){
				ans += binom(freedom, now_empty) * fact[now_empty] * fact[all_empty - now_empty];
			}
		}
	}
	cout << ans.val() << '\n';
}