#include <bits/stdc++.h>
using namespace std;
string to_string(string s) { return '"' + s + '"'; }
string to_string(bool x) { return (x ? "T" : "F"); }
string to_string(const char* s) { return to_string((string)s); }
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename V>
string to_string(V v) {
  bool f = true;
  string res = "[";
  for (const auto& x : v) {
    if (!f) res += ", ";
    f = false;
    res += to_string(x);
  }
  res += "]";
  return res;
}
void debug() { cerr << endl; }
template <typename H, typename... T>
void debug(H h, T... t) {
  cerr << " " << to_string(h);
  debug(t...);
}
const int MOD = 998244353;
template <typename T>
struct modular {
  constexpr modular() : val(0) {}
  constexpr modular(const modular<T>& _m) : val(_m.val) {}
  template <typename U>
  constexpr modular(const U& _r = U()) {
    val = -MOD <= _r && _r < MOD ? _r : _r % MOD;
    if (val < 0) {
      val += MOD;
    }
  }
  const T operator()() { return val; }
  template <typename U>
  explicit operator U() const {
    return static_cast<U>(val);
  }
  modular<T>& operator+=(const modular<T>& _m) {
    if ((val += _m.val) >= MOD) {
      val -= MOD;
    }
    return *this;
  }
  modular<T>& operator-=(const modular<T>& _m) {
    if ((val -= _m.val) < 0) {
      val += MOD;
    }
    return *this;
  }
  modular<T>& operator*=(const modular<T>& _m) {
    val = modular<T>(static_cast<int64_t>(val) * static_cast<int64_t>(_m.val))
              .val;
    return *this;
  }
  modular<T>& operator/=(const modular<T>& _m) {
    T a = _m.val, b = MOD, u = 0, v = 1;
    while (a != 0) {
      T q = b / a;
      b -= q * a;
      swap(a, b);
      u -= q * v;
      swap(u, v);
    }
    return *this *= u;
  }
  modular<T>& operator=(const modular<T>& _m) {
    val = _m.val;
    return *this;
  }
  template <typename U>
  modular<T>& operator+=(const U& _r) {
    return *this += modular<T>(_r);
  }
  template <typename U>
  modular<T>& operator-=(const U& _r) {
    return *this -= modular<T>(_r);
  }
  template <typename U>
  modular<T>& operator*=(const U& _r) {
    return *this *= modular<T>(_r);
  }
  template <typename U>
  modular<T>& operator/=(const U& _r) {
    return *this /= modular<T>(_r);
  }
  template <typename U>
  modular<T>& operator=(const U& _r) {
    val = modular<T>(_r).val;
    return *this;
  }
  modular<T> operator-() { return modular<T>(-val); }
  template <typename U>
  friend bool operator==(const modular<U>&, const modular<U>&);
  friend std::istream& operator>>(std::istream& os, modular<T>& _m) {
    os >> _m.val;
    _m *= 1;
    return os;
  }
  friend std::ostream& operator<<(std::ostream& os, const modular<T>& _m) {
    return os << _m.val;
  }
  template <typename U>
  modular<T> exp(U e) {
    modular<T> res = 1;
    modular<T> b = val;
    if (e < 0) {
      b = 1 / b;
      e *= -1;
    }
    for (; e; e >>= 1) {
      if (e & 1) {
        res *= b;
      }
      b *= b;
    }
    return res;
  }

 private:
  T val;
};
template <typename T>
inline modular<T> operator+(const modular<T>& _lhs, const modular<T>& _rhs) {
  return modular<T>(_lhs) += _rhs;
}
template <typename T, typename U>
inline modular<T> operator+(const modular<T>& _lhs, const U& _rhs) {
  return modular<T>(_lhs) += _rhs;
}
template <typename T, typename U>
inline modular<T> operator+(const U& _lhs, const modular<T>& _rhs) {
  return modular<T>(_lhs) += _rhs;
}
template <typename T>
inline modular<T> operator-(const modular<T>& _lhs, const modular<T>& _rhs) {
  return modular<T>(_lhs) -= _rhs;
}
template <typename T, typename U>
inline modular<T> operator-(const modular<T>& _lhs, const U& _rhs) {
  return modular<T>(_lhs) -= _rhs;
}
template <typename T, typename U>
inline modular<T> operator-(const U& _lhs, const modular<T>& _rhs) {
  return modular<T>(_lhs) -= _rhs;
}
template <typename T>
inline modular<T> operator*(const modular<T>& _lhs, const modular<T>& _rhs) {
  return modular<T>(_lhs) *= _rhs;
}
template <typename T, typename U>
inline modular<T> operator*(const modular<T>& _lhs, const U& _rhs) {
  return modular<T>(_lhs) *= _rhs;
}
template <typename T, typename U>
inline modular<T> operator*(const U& _lhs, const modular<T>& _rhs) {
  return modular<T>(_lhs) *= _rhs;
}
template <typename T>
inline modular<T> operator/(const modular<T>& _lhs, const modular<T>& _rhs) {
  return modular<T>(_lhs) /= _rhs;
}
template <typename T, typename U>
inline modular<T> operator/(const modular<T>& _lhs, const U& _rhs) {
  return modular<T>(_lhs) /= _rhs;
}
template <typename T, typename U>
inline modular<T> operator/(const U& _lhs, const modular<T>& _rhs) {
  return modular<T>(_lhs) /= _rhs;
}
template <typename T>
inline bool operator==(const modular<T>& _lhs, const modular<T>& _rhs) {
  return _lhs.val == _rhs.val;
}
template <typename T, typename U>
inline bool operator==(const modular<T>& _lhs, const U& _rhs) {
  return _lhs == modular<T>(_rhs);
}
template <typename T, typename U>
inline bool operator==(const U& _lhs, const modular<T>& _rhs) {
  return modular<T>(_lhs) == _rhs;
}
template <typename T>
inline bool operator!=(const modular<T>& _lhs, const modular<T>& _rhs) {
  return !(_lhs == _rhs);
}
template <typename T, typename U>
inline bool operator!=(const modular<T>& _lhs, const U& _rhs) {
  return !(_lhs == _rhs);
}
template <typename T, typename U>
inline bool operator!=(const U& _lhs, const modular<T>& _rhs) {
  return !(_lhs == _rhs);
}
void solve() {
  int n;
  cin >> n;
  vector<int> a(n), b(2 * n), c(n, 0);
  for (int i = 0; i < n; i++) {
    int x;
    cin >> x;
    x--;
    b[i] = b[i + n] = a[i] = x;
    c[x]++;
  }
  2019;
  if (c[0] == 0) {
    cout << 0;
    return;
  }
  if (c[0] == n) {
    modular<int> res = 1;
    for (int i = 1; i <= n; i++) {
      res *= i;
    }
    cout << res;
    return;
  }
  for (int i = 1; i <= n; i++) {
    if (b[i] == 0 && b[i - 1] != 0) {
      for (int j = 0; j < n; j++) {
        a[j] = b[i + j];
      }
    }
  }
  2019;
  vector<int> L(n, -1), R(n, -2);
  for (int i = 0; i < n; i++) {
    R[a[i]] = i;
  }
  for (int i = n - 1; i >= 0; i--) {
    L[a[i]] = i;
  }
  for (int i = 0; i < n; i++) {
    if (R[i] - L[i] + 1 != c[i]) {
      cout << 0;
      return;
    }
  }
  2019;
  modular<int> res = 1;
  int fre = 0;
  int K = c[0];
  vector<bool> useoth(n, false);
  for (int x = 0; x < n; x++) {
    2019;
    if (c[x] == 0) {
      res *= fre--;
      continue;
    }
    if (c[x] > K) {
      cout << 0;
      return;
    }
    int l = (L[x] + n - 1) % n, r = (R[x] + 1) % n;
    if (a[l] > x && x < a[r]) {
      if (c[x] != K) {
        cout << 0;
        return;
      }
      continue;
    }
    if (a[l] < x && x > a[r]) {
      res *= K - c[x] + 1;
      fre += c[a[l]] - 1 + useoth[a[l]];
      fre += c[x] - 1;
      continue;
    }
    if (a[l] > x && x > a[r]) {
      fre += c[x] - 1;
      continue;
    }
    if (a[l] < x && x < a[r]) {
      fre += c[a[l]] - 1 + useoth[a[l]];
      if (c[x] < K) {
        useoth[x] = true;
        fre--;
      }
    }
  }
  cout << res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  solve();
  cout << endl;
}
