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

#include<atcoder/all>
using namespace atcoder;
using mint = modint998244353;
vector<mint> fact, factinv, inv;
const ll mod = 998244353;
void prenCkModp(ll n) {
    fact.resize(n + 5);
    factinv.resize(n + 5);
    inv.resize(n + 5);
    fact[0] = fact[1] = 1;
    factinv[0] = factinv[1] = 1;
    inv[1] = 1;
    for (ll i = 2; i < n + 5; i++) {
        fact[i] = (fact[i - 1] * i);
        inv[i] = mod - (inv[mod % i] * (mod / i));
        factinv[i] = (factinv[i - 1] * inv[i]);
    }

}

mint nCk(ll n, ll k) {
    if (n < k||k<0) return 0;
    return fact[n] * (factinv[k] * factinv[n - k]);
}


int main(){

    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    
    ll N;
    cin>>N;
    vector<bool> U(N,0);
    vector<ll> A(N);
    ll z=N;
    for(int i=0;i<N;i++){
        cin>>A[i];
        if(A[i]>0){
            z--;
            A[i]--;
            U[A[i]]=1;
        }
    } 
    vector<ll> Z;
    prenCkModp(N+1);
    for(int i=0;i<N;i++)if(!U[i])Z.push_back(i);
    mint an=0;
    ll h=-1;
    ll c=0;
    for(int i=0;i<N;i++){
        if(A[i]>=0){
            if(h>A[i])continue;
            ll zp=lower_bound(Z.begin(),Z.end(),A[i])-Z.begin();
            an+=nCk(zp,c)*fact[c]*fact[z-c];
            h=max(h,A[i]);
        }
        else{
            c++;
            
            ll zp=lower_bound(Z.begin(),Z.end(),h)-Z.begin();
            mint res=nCk(z,c)*fact[c-1]*fact[z-c];
            res-=nCk(zp,c)*fact[c-1]*fact[z-c];
            an+=res;
        }
    }
    cout<<an.val()<<endl;
}