#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using Graph = vector<vector<int> >;
using mint = modint998244353;
const int INF = 1e9;
const int MOD = 1e9+7;
const ll LINF = 1e+18;

#define REP(i, n) for (int i = 0; (i) < (int)(n); ++ (i))
#define REP2(i, s, n) for (int i = (s); i < (int)(n); i++)
#define YesNo(T) if(T){cout<<"Yes"<<endl;}else{cout<<"No"<<endl;}
#define ALL(x) x.begin(),x.end()
#define VI vector<int>
#define VL vector<ll>
#define VC vector<char>
#define VVI vector<vector<int> >
#define VVL vector<vector<ll> >
#define VVC vector<vector<char> >
#define VPII vector<pair<int,int> >
#define VPLL vector<pair<ll,ll> >

template <class T>
	inline void printVec(std::vector<T> v){
	REP(i,v.size()){
	if(i) std::cout << " ";
	std::cout << v[i];
	} std::cout << std::endl;
}

int main() {
	cin.tie(0);
	ios_base::sync_with_stdio(false);
	int n;
	cin >> n;
	VI p(n);
	REP(i,n) cin >> p[i];
	int cnt = n - 1;
	int mi = 0;
	REP(i,n) if(p[i] == i + 1) cnt--;
	REP(i,n){
		if(p[p[i] - 1] == i + 1){
			mi++;
		}
	}
	mi /= 2;
	cout << max(0,cnt - mi) << endl;
}