#include <bits/stdc++.h>
using namespace std;
inline int rei() {
  int x;
  cin >> x;
  return x;
}
inline long long rel() {
  long long x;
  cin >> x;
  return x;
}
inline string res() {
  string x;
  cin >> x;
  return x;
}
template <typename TTT>
struct SegTree {
  int sz;
  vector<TTT> X;
  SegTree(int N) {
    sz = 1;
    while (sz < N) sz <<= 1;
    X.assign(2 * sz, 0);
  }
  TTT f(TTT a, TTT b) { return a + b; }
  void Set(int k, const TTT x) { X[k + sz] = x; }
  void Build() {
    for (int k = sz - 1; k > 0; k--) {
      X[k] = f(X[2 * k], X[2 * k + 1]);
    }
  }
  void Update(int k, const TTT x) {
    k += sz;
    X[k] = x;
    while (k >>= 1) {
      X[k] = f(X[2 * k + 0], X[2 * k + 1]);
    }
  }
  TTT Query(int a, int b) {
    TTT L = 0, R = 0;
    for (a += sz, b += sz + 1; a < b; a >>= 1, b >>= 1) {
      if (a & 1) L = f(L, X[a++]);
      if (b & 1) R = f(X[--b], R);
    }
    return f(L, R);
  }
};
int A0[300000];
int A[300000];
int firstplace[300000];
int number[300000];
int minn[300000];
int enableplace[300000];
vector<int> query[300000];
void Calc() {
  int N = rei();
  for (int i = 0; i < N; i++) {
    A0[i] = rei() - 1;
  }
  bool ALLzero = true;
  for (int i = 0; i < N; i++) {
    ALLzero &= A0[i] == 0;
  }
  if (ALLzero) {
    long long c = 1;
    for (int i = 1; i <= N; i++) {
      c *= i;
      c %= 1000000007;
    }
    cout << c << endl;
    return;
  }
  int firstzero = -1;
  if (A0[0] == 0 && A0[N - 1] != 0) {
    firstzero = 0;
  } else {
    for (int i = 1; i < N; i++) {
      if (A0[i] == 0 && A0[i - 1] != 0) {
        firstzero = i;
        break;
      }
    }
  }
  if (firstzero == -1) {
    cout << 0 << endl;
    return;
  }
  for (int i = 0; i < N; i++) {
    A[i] = A0[(i + firstzero) % N];
    firstplace[i] = -1;
  }
  for (int i = 0; i < N; i++) {
    number[A[i]]++;
    if (firstplace[A[i]] == -1) {
      firstplace[A[i]] = i;
    } else if (A[i] != A[i - 1]) {
      cout << 0 << endl;
      return;
    }
  }
  int n = number[0];
  if (n == 1) {
    for (int i = 0; i < N; i++) {
      if (number[i] != 1) {
        cout << 0 << endl;
        return;
      }
    }
    cout << 1 << endl;
    return;
  }
  deque<int> deq;
  for (int i = 0; i < n; i++) {
    deq.push_back(A[i]);
  }
  minn[0] = 0;
  query[0].push_back(0);
  for (int i = 1; i < N; i++) {
    if (deq.front() == A[i - 1]) {
      deq.pop_front();
    }
    if (i + n - 1 < N) {
      while (!deq.empty() && deq.back() < A[i + n - 1]) {
        deq.pop_back();
      }
      deq.push_back(A[i + n - 1]);
    }
    minn[i] = deq.front();
    query[minn[i]].push_back(i);
  }
  for (int i = 0; i < N; i++) {
    enableplace[minn[i]]++;
  }
  for (int i = 1; i < N; i++) {
    enableplace[i] += enableplace[i - 1];
  }
  SegTree<int> Seg(N);
  long long ans = 1;
  for (int j : query[0]) {
    Seg.Update(j, 1);
  }
  for (int i = 1; i < N; i++) {
    if (number[i] == 0) {
      ans *= enableplace[i] - i;
    } else {
      for (int j : query[i]) {
        Seg.Update(j, 1);
      }
      int from = firstplace[i] + number[i] - n;
      int to = firstplace[i];
      if (from > to) {
        cout << 0 << endl;
        return;
      }
      ans *= Seg.Query(from, to);
    }
    ans %= 1000000007;
  }
  cout << ans << endl;
}
int main(int argc, char** argv) {
  ios::sync_with_stdio(false), cin.tie(0);
  cout.tie(0);
  Calc();
  return 0;
}
