// Slower C++ solution:
#include<iostream>

#include<map>

#include<set>

#include<string>

#include<algorithm>

#include<cmath>

#include<vector>

#include<queue>

#include<stack>



using namespace std;



typedef long long ll;

typedef unsigned long long ull;

typedef int itn;



const int inf = 99999999;

const ll linf = 999999999999999999;

const double pi = acos(-1);

const int dx[4]={1,0,-1,0};

const int dy[4]={0,1,0,-1};



#define p_queue(i) priority_queue<i> 

#define rp_queue(i) priority_queue<i, vector<i>, greater<i>> 

#define P(p) cout<<(p)<<endl

#define rep(i,m,n) for(int i = (m); i < (int)(n); i++)

#define mod(i) ((i)%(ll)(1e9 + 7))

#define divm(a,b) (mod(a * modpow((ll)b,(ll)(1e9+5))))

#define rsort(a,b,c) sort(a, b, greater<c>())

#define vsort(v) sort(v.begin(), v.end());

#define rvsort(v) sort(v.end(), v.begin());

#define ft first

#define sd second

#define pb push_back

#define it insert

#define sz(x) ((int)(x).size())

#define lb(a,n,k) (lower_bound(a,a+n,k) - a) 

#define vlb(a,k)  (lower_bound(a.begin(),a.end(),k) - a.begin())

#define YES cout<<"YES"<< endl

#define NO cout<<"NO"<<endl

#define Yes cout<<"Yes"<<endl

#define No cout<<"No"<<endl  

#define yes cout<<"yes"<<endl

#define no cout<<"no"<<endl

#define ret return



ll modpow(ll i,ll j){ ll tmp=1; while(j){ if(j%2)tmp=mod(tmp*i);i=mod(i*i);j/=2;}return tmp;}

ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}

ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }



//ll ncr[100][100];

//ll nCr(int n, int r){if(n==r) ret ncr[n][r] = 1; if(r==0) ret ncr[n][r] = 1; if(r==1) ret ncr[n][r] = n;if(ncr[n][r]) ret ncr[n][r]; ret ncr[n][r] = nCr(n-1,r) + nCr(n-1,r-1);}



//ll npr[100][100]={};

//ll nPr(int n,int r){if(npr[n][r])ret npr[n][r];if(r==0)ret npr[n][r] = 1;if(r==1)ret npr[n][r] = n;ret npr[n][r] = n * nPr(n-1,r-1);}



//ll nHr(int n,int r){ret nCr(n+r-1,r);}



///////////////////////////////////////////////////////////////////////////







int main(){

	int n;

	cin >> n;

	int a[100005] = {};

	rep(i,1,n+1)cin >> a[i];



	int ans = 0;

	rep(i,1,n+1){

        if(a[a[i]] == i)ans++;  

	}

	P(ans/2);

	return  0;

}

// Faster C++ solution for the same problem (measured speedup: 1.3790631259290438x):
#include<iostream>

#include<map>

#include<set>

#include<string>

#include<algorithm>

#include<cmath>

#include<vector>

#include<queue>

#include<stack>

#include<limits>

#include<sstream>      



using namespace std;



typedef long long ll;

typedef unsigned long long ull;

typedef int itn;



const int inf = numeric_limits<int>::max() /4;

const ll linf = numeric_limits<ll>::max() /4;

const ull ulinf = numeric_limits<ull>::max()/4;

const double pi = acos(-1);

const int dx[4]={1,0,-1,0};

const int dy[4]={0,1,0,-1};

const int dx8[8]={-1,0,1,-1,1,-1,0,1};

const int dy8[8]={-1,-1,-1,0,0,1,1,1};



#define p_queue(i) priority_queue<i> 

#define rp_queue(i) priority_queue<i, vector<i>, greater<i>> 

#define P(p) cout<<(p)<<endl

#define rep(i,m,n) for(int i = (m); i < (int)(n); i++)

#define mod(i) ((i)%(ll)(1e9 + 7))

#define divm(a,b) (mod(a * modpow((ll)b,(ll)(1e9+5))))

#define rsort(a,b,c) sort(a, b, greater<c>())

#define vsort(v) sort(v.begin(), v.end());

#define rvsort(v) sort(v.end(), v.begin());

#define ft first

#define sd second

#define pb push_back

#define it insert

#define sz(x) ((int)(x).size())

#define lb(a,n,k) (lower_bound(a,a+n,k) - a) 

#define vlb(a,k)  (lower_bound(a.begin(),a.end(),k) - a.begin())

#define ub(a,n,k) (upper_bound(a,a+n,k) - a) 

#define vub(a,k)  (upper_bound(a.begin(),a.end(),k) - a.begin())

#define YES cout<<"YES"<< endl

#define NO cout<<"NO"<<endl

#define Yes cout<<"Yes"<<endl

#define No cout<<"No"<<endl  

#define yes cout<<"yes"<<endl

#define no cout<<"no"<<endl

#define ret return



ll modpow(ll i,ll j){ ll tmp=1; while(j){ if(j%2)tmp=mod(tmp*i);i=mod(i*i);j/=2;}return tmp;}

ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}

ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }



vector<string> split(const string &str, char sep){

    vector<string> v;

    stringstream ss(str);

    string buffer;

    while( getline(ss, buffer, sep) ) {

        v.push_back(buffer);

    }

    return v;

}



//ll ncr[100][100];

//ll nCr(int n, int r){if(n==r) ret ncr[n][r] = 1; if(r==0) ret ncr[n][r] = 1; if(r==1) ret ncr[n][r] = n;if(ncr[n][r]) ret ncr[n][r]; ret ncr[n][r] = nCr(n-1,r) + nCr(n-1,r-1);}



//ll npr[100][100]={};

//ll nPr(int n,int r){if(npr[n][r])ret npr[n][r];if(r==0)ret npr[n][r] = 1;if(r==1)ret npr[n][r] = n;ret npr[n][r] = n * nPr(n-1,r-1);}



//ll nHr(int n,int r){ret nCr(n+r-1,r);}



///////////////////////////////////////////////////////////////////////////



int n,m,a,b,c,d[100005] = {};

string s,t;



int main(){

    cin >> n ;//>> m;

    rep(i,1,n+1)cin >> d[i];



    int ans = 0;

    rep(i,1,n+1){

        if(d[d[i]] == i)ans++;

    }

    P(ans/2);

	

	return  0;

}