#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int temp[100012], arr[100012], t[100012];
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
    t[i] = arr[i];
  }
  sort(t, t + n);
  int v = 0;
  for (int i = 0; i < n; i++) {
    if (t[i] != arr[i]) {
      v = 1;
      break;
    }
  }
  if (v == 0) {
    cout << n << endl;
    return 0;
  }
  int c = 0;
  for (int i = 0; i < n; i++) {
    if (arr[i] == i)
      c++;
    else {
      temp[i] = arr[i];
    }
  }
  int f = 0;
  for (int i = 0; i < n; i++) {
    if (arr[i] != i) {
      if (i == temp[temp[i]]) {
        c += 2;
        f = 1;
        break;
      }
    }
  }
  if (f == 0) c += 1;
  if (c > n) c = n;
  cout << c << endl;
}
