#include <iostream>
#include <vector>
using namespace std;

#include <atcoder/modint>
using namespace atcoder;

using mint = modint998244353;

const int MAX = 201000;
constexpr long long MOD = 998244353;

vector<mint> fac(MAX), finv(MAX), inv(MAX);
// i!, 1/i, 1/i!

void COMinit(){
    fac[0] = 1;
    fac[1] = 1;
    finv[0] = 1;
    finv[1] = 1;
    inv[1] = 1;
    
    for(int i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i;
        inv[i] = -inv[MOD % i] * (MOD / i);
        finv[i] = finv[i - 1] * inv[i];
    }
}

mint COM(int n, int k){
    if(n < k || n < 0 || k < 0){
        return 0;
    }
    return fac[n] * finv[k] * finv[n - k];
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    COMinit();

    int n;
    cin >> n;

    int m = 0;
    vector<int> a(n), b, exist(n, 0);
    for(int i = 0; i < n; i++){
        cin >> a[i];
        if(a[i] == -1){
            m++;
        }
        else{
            a[i]--;
            exist[a[i]] = 1;
        }
    }

    for(int i = 0; i < n; i++){
        if(exist[i] == 0){
            b.emplace_back(i);
        }
    }

    mint ans = 0;
    int x = 0, mx = -1;
    for(int i = 0; i < n; i++){
        if(a[i] != -1){
            mx = max(mx, a[i]);
            if(mx != a[i]){
                continue;
            }
            int y = lower_bound(b.begin(), b.end(), mx) - b.begin();
            ans += COM(y, x) / COM(m, x);
        }
        else{
            int j = lower_bound(b.begin(), b.end(), mx) - b.begin() + 1;
            j = max(j, x + 1);
            ans += (COM(m, x + 1) - COM(j - 1, x + 1)) / (m * COM(m - 1, x));

            x++;
        }
    }

    for(int i = 1; i <= m; i++){
        ans *= i;
    }

    cout << ans.val() << endl;
}