#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;
using mint = modint998244353;


constexpr int FACT_SIZE = 1000000;
mint Fact[FACT_SIZE + 1];
mint iFact[FACT_SIZE + 1];
const auto fact_init = [] {
    Fact[0] = mint::raw(1);
    for(int i = 1; i <= FACT_SIZE; ++i) {
        Fact[i] = Fact[i-1] * i;
    }
    iFact[FACT_SIZE] = Fact[FACT_SIZE].inv();
    for(int i = FACT_SIZE; i; --i) {
        iFact[i-1] = iFact[i] * i;
    }
    return false;
}();

mint comb(int n, int k) {
    if (k == 0) return mint::raw(1);
    assert(n >= 0 && k >= 0);
    if (k > n) return mint::raw(0);
    return Fact[n] * iFact[n - k] * iFact[k];
}

mint icomb(int n, int k) {
    return iFact[n] * Fact[n - k] * Fact[k];
}

mint fact(int n) {return Fact[n];}
mint perm(int n, int k) {
    if (n < k) return 0;
    assert(0 <= n);
    return Fact[n] * iFact[n - k];
}

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  VI a(n);
  rep(i, n) cin >> a[i], a[i]--;
  if (*max_element(all(a)) != n - 1) {
    cout << 0 << '\n';
    return 0;
  }
  vector<VVI> req(n);
  rep(i, n) {
    VI d;
    rep(s, n) if (a[s] == n - 1) {
      d.emplace_back((i - s + n) % n);
    }
    req[a[i]].emplace_back(d);
  }
  vector<char> used(n);
  mint ans = 1;
  int cnt = 0;
  rep(v, n - 1) if (req[v].size()) {
    VI freq(n);
    for (auto& d : req[v]) {
      for (int i : d) if (!used[i]) {
        freq[i]++;
      }
    }
    int news = 0, cand = 0;
    rep(i, n) if (freq[i]) {
      news++;
      cand += freq[i] == ssize(req[v]);
      used[i] = true;
    }
    if (cnt + news > v + 1) {
      ans = 0;
      break;
    }
    ans *= cand;
    cnt++;
    news--;
    ans *= perm(v + 1 - cnt, news);
    cnt += news;
  }
  ans *= Fact[n - 1 - cnt];
  ans *= n;
  cout << ans.val() << '\n';
}