#include <bits/stdc++.h>

using namespace std;
using ll = long long;

const int N = 2e5 + 10, mod = 998244353;

int n, a[N], cnt[N], mmax, ct, c;
bool f[N];
ll ans, fact[N], factinv[N], inv[N];

ll C(int n, int m) {
    return fact[n] * factinv[m] % mod * factinv[n - m] % mod;
}

int main() {
    ios::sync_with_stdio(0), cin.tie(0);
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i], f[a[i]] = 1;
    for (int i = 1; i <= n; i++) ct += a[i] == -1;

    inv[1] = 1;
    for (int i = 2; i <= n; i++) {
        inv[i] = (mod - mod / i) * inv[mod % i] % mod;
    }
    fact[0] = factinv[0] = 1;
    for (int i = 1; i <= n; i++) {
        fact[i] = fact[i - 1] * i % mod;
        factinv[i] = factinv[i - 1] * inv[i] % mod;
    }

    for (int i = 1; i <= n; i++) cnt[i] = cnt[i - 1] + !f[i];
    for (int i = 1; i <= n; i++) {
        mmax = max(mmax, a[i]);
        if (a[i] == -1) c++, (ans += (C(ct, c) - C(cnt[mmax - 1], c) + mod) % mod * fact[c - 1] % mod * fact[ct - c] % mod) %= mod;
        else if (mmax == a[i] && cnt[mmax - 1] >= c) (ans += C(cnt[mmax - 1], c) * fact[c] % mod * fact[ct - c] % mod) %= mod;
    }
    cout << ans;
    return 0;
}