#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i,s,n) for (int i = (s); i < (n); ++i)
#define rrep(i,g,n) for (int i = (n)-1; i >= (g); --i)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define len(x) (int)(x).size()
#define dup(x,y) (((x)+(y)-1)/(y))
#define pb push_back
#define eb emplace_back
#define Field(T) vector<vector<T>>
using namespace std;
using ll = long long;
using ull = unsigned long long;
template<typename T> using pq = priority_queue<T,vector<T>,greater<T>>;
using P = pair<int,int>;
template<class T>bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T&a,T b){if(b<a){a=b;return 1;}return 0;}

class UnionFind {
 public:
  int n, cnt;
  vector <int> par;
  vector <int> siz;

  UnionFind(int sz_): n(sz_), cnt(sz_), par(sz_), siz(sz_, 1) {
    for (int i = 0; i < sz_; ++i) par[i] = i;
  }
  void init(int sz_) {
    n = sz_, cnt = sz_;
    par.resize(sz_);
    siz.assign(sz_, 1);
    for (int i = 0; i < sz_; ++i) par[i] = i;
  }

  int root(int x) {
    if (par[x] == x) {
      return x;
    } else {
      int r = root(par[x]);
      return par[x] = r;
    }
  }

  bool merge(int x, int y) {
    x = root(x);
    y = root(y);
    if (x == y) return false;
    if (siz[x] < siz[y]) swap(x, y);
    siz[x] += siz[y];
    par[y] = x;
    --cnt;
    return true;
  }

  bool is_same(int x, int y) {
    return root(x) == root(y);
  }

  int size(int x) {
    return siz[root(x)];
  }

  int group_cnt() {
    return cnt;
  }

  vector<vector<int>> groups() {
    vector<vector<int>> ret(n);
    for (int i = 0; i < n; ++i) {
      ret[root(i)].emplace_back(i);
    }
    ret.erase(remove_if(ret.begin(), ret.end(), [](const vector<int> &v) {
      return v.empty();
    }), ret.end());
    return ret;
  }
};

int main() {
  int n;
  cin >> n;
  UnionFind uf(n);
  vector<int> a(n);
  rep(i,0,n) {
    cin >> a[i], --a[i];
    uf.merge(i, a[i]);
  }
  cout << uf.group_cnt() << endl;
  return 0;
}