Problem: PolandBall lives in a forest with his family. There are some trees in the forest. Trees are undirected acyclic graphs with k vertices and k - 1 edges, where k is some integer. Note that one vertex is a valid tree.

There is exactly one relative living in each vertex of each tree, they have unique ids from 1 to n. For each Ball i we know the id of its most distant relative living on the same tree. If there are several such vertices, we only know the value of the one with smallest id among those.

How many trees are there in the forest?

Input

The first line contains single integer n (1 ≤ n ≤ 104) — the number of Balls living in the forest.

The second line contains a sequence p1, p2, ..., pn of length n, where (1 ≤ pi ≤ n) holds and pi denotes the most distant from Ball i relative living on the same tree. If there are several most distant relatives living on the same tree, pi is the id of one with the smallest id.

It's guaranteed that the sequence p corresponds to some valid forest.

Hacking: To hack someone, you should provide a correct forest as a test. The sequence p will be calculated according to the forest and given to the solution you try to hack as input. Use the following format:

In the first line, output the integer n (1 ≤ n ≤ 104) — the number of Balls and the integer m (0 ≤ m < n) — the total number of edges in the forest. Then m lines should follow. The i-th of them should contain two integers ai and bi and represent an edge between vertices in which relatives ai and bi live. For example, the first sample is written as follows:
    
    
      
    5 3  
    1 2  
    3 4  
    4 5  
    

Output

You should output the number of trees in the forest where PolandBall lives.

Interaction

From the technical side, this problem is interactive. However, it should not affect you (except hacking) since there is no interaction.

Examples

Input

5
2 1 5 3 3

Output

2

Input

1
1


Output

1

Note

In the first sample testcase, possible forest is: 1-2 3-4-5. 

There are 2 trees overall.

In the second sample testcase, the only possible graph is one vertex and no edges. Therefore, there is only one tree.

Solution (in JAVA):

Solution:
/*
 
    /$$$$$  /$$$$$$  /$$    /$$  /$$$$$$                                                                  
   |__  $$ /$$__  $$ |$$    |$$ /$$__  $$                                                                 
          | $$| $$  \ $$|    $$|$$| $$  \ $$                                                                 
          | $$| $$$$$$$$|  $$ / $$/| $$$$$$$$                                                                 
/ $$  | $$| $$__  $$ \  $$ $$/ | $$__  $$                                                                 
| $$  | $$| $$  | $$  \  $$$/  | $$  | $$                                                                 
|  $$$$$$/| $$  | $$   \  $/   | $$  | $$                                                                 
 \______/ |__/  |__/    \_/    |__/  |__/    
 
/$$$$$$$  /$$$$$$$   /$$$$$$   /$$$$$$  /$$$$$$$   /$$$$$$  /$$      /$$ /$$      /$$ /$$$$$$$$ /$$$$$$$ 
| $$__  $$| $$__  $$ /$$__  $$ /$$__  $$| $$__  $$ /$$__  $$| $$$    /$$$| $$$    /$$$| $$_____/| $$__  $$
| $$  \ $$| $$  \ $$| $$  \ $$| $$  \__/| $$  \ $$| $$  \ $$| $$$$  /$$$$| $$$$  /$$$$| $$      | $$  \ $$
| $$$$$$$/| $$$$$$$/| $$  | $$| $$ /$$$$| $$$$$$$/| $$$$$$$$| $$ $$/$$ $$| $$ $$/$$ $$| $$$$$   | $$$$$$$/
| $$____/ | $$__  $$| $$  | $$| $$|_  $$| $$__  $$| $$__  $$| $$  $$$| $$| $$  $$$| $$| $$__/   | $$__  $$
| $$      | $$  \ $$| $$  | $$| $$  \ $$| $$  \ $$| $$  | $$| $$\  $ | $$| $$\  $ | $$| $$      | $$  \ $$
| $$      | $$  | $$|  $$$$$$/|  $$$$$$/| $$  | $$| $$  | $$| $$ \/  | $$| $$ \/  | $$| $$$$$$$$| $$  | $$
|__/      |__/  |__/ \______/  \______/ |__/  |__/|__/  |__/|__/     |__/|__/     |__/|________/|__/  |__/
                                                                                                           
                                                                                                                                                                                                                 
                                                                                                                                                                                                                
 
*/
////solution at bottom 
import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
 public class codeforces
{
    static void shuffle( int arr[])
    {
        int n = arr.length;
        Random r = new Random();
         
       for (int i = n-1; i > 0; i--) {
           int j = r.nextInt(i+1);
             
            int temp = arr[i];
            arr[i] = arr[j];
            arr[j] = temp;
        }
    }
    static void shuffle( int arr[][])
    {
        int n = arr.length;
        Random r = new Random();
         
       for (int i = n-1; i > 0; i--) {
           int j = r.nextInt(i+1);
             
            int[] temp = arr[i];
            arr[i] = arr[j];
            arr[j] = temp;
        }
    }
    
    static class FastReader 
    { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader() 
        { 
            br = new BufferedReader(new
                     InputStreamReader(System.in)); 
        } 
  
        String next() 
        { 
            while (st == null || !st.hasMoreElements()) 
            { 
                try
                { 
                    st = new StringTokenizer(br.readLine()); 
                } 
                catch (IOException  e) 
                { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        }
        int[][] tdiarr(int m , int n){
            int[][] a = new int[m][n];
            for(int i=0;i<m;i++){
                for(int j=0;j<n;j++){
                    a[i][j]=Integer.parseInt(next());
                }
            }
            return a;
        } 
        int[] niarr(int n)
        {
            int[] a = new int[n];
            for(int i=0;i<n;i++)a[i]=Integer.parseInt(next());
            return a;
        }
        long[] nlarr(int n)
        {
            long[] a = new long[n];
            for(int i=0;i<n;i++)a[i]=Long.parseLong(next());
            return a;
        }
        char[] ncarr(){
            return next().trim().toCharArray();
            
            
        }
        
  
        int ni() 
        { 
            return Integer.parseInt(next()); 
        } 
  
        long nl() 
        { 
            return Long.parseLong(next()); 
        } 
  
        double nd() 
        { 
            return Double.parseDouble(next()); 
        } 
  
        String nstr() 
        { 
            String str = ""; 
            try
            { 
                str = br.readLine(); 
            } 
            catch (IOException e) 
            { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    }
    
    static void SegmentTree(int arr[], int n)
    {
        // Allocate memory for segment tree
        //Height of segment tree
        int x = (int) (Math.ceil(Math.log(n) / Math.log(2)));
 
        //Maximum size of segment tree
        int max_size = 2 * (int) Math.pow(2, x) - 1;
 
         int[] st = new int[max_size]; // Memory allocation
 
        constructSTUtil(arr, 0, n - 1, 0);
    }
    static int constructSTUtil(int arr[], int ss, int se, int si)
    {
        // If there is one element in array, store it in current node of
        // segment tree and return
        if (ss == se) {
            st[si] = arr[ss];
            return arr[ss];
        }
 
        // If there are more than one elements, then recur for left and
        // right subtrees and store the sum of values in this node
        int mid = getMid(ss, se);
        st[si] = Math.min(constructSTUtil(arr, ss, mid, si * 2 + 1) ,
                 constructSTUtil(arr, mid + 1, se, si * 2 + 2));
        return st[si];
    }
    static int getMid(int s, int e) {
        return s + (e - s) / 2;
    }
    static int getSum(int n, int qs, int qe)
    {
        // Check for erroneous input values
        if (qs < 0 || qe > n - 1 || qs > qe) {
           // System.out.println("Invalid Input");
            return -1;
        }
        return getSumUtil(0, n - 1, qs, qe, 0);
    }
    static int getSumUtil(int ss, int se, int qs, int qe, int si)
    {
        // If segment of this node is a part of given range, then return
        // the sum of the segment
        if (qs <= ss && qe >= se)
            return st[si];
 
        // If segment of this node is outside the given range
        if (se < qs || ss > qe)
            return Integer.MAX_VALUE;
 
        // If a part of this segment overlaps with the given range
        int mid = getMid(ss, se);
        return Math.min(getSumUtil(ss, mid, qs, qe, 2 * si + 1) ,
                getSumUtil(mid + 1, se, qs, qe, 2 * si + 2));
    }
    static void updateValue(int arr[], int n, int i, int new_val)
    {
        // Check for erroneous input index
        if (i < 0 || i > n - 1) {
//            System.out.println("Invalid Input");
            return;
        }
 
        // Get the difference between new value and old value
        int diff = new_val - arr[i];
 
        // Update the value in array
        arr[i] = new_val;
 
        // Update the values of nodes in segment tree
        updateValueUtil(0, n - 1, i, diff, 0);
    }
    static void updateValueUtil(int ss, int se, int i, int diff, int si)
    {
        // Base Case: If the input index lies outside the range of
        // this segment
        if (i < ss || i > se)
            return;
 
        // If the input index is in range of this node, then update the
        // value of the node and its children
        st[si] = st[si] + diff;
        if (se != ss) {
            int mid = getMid(ss, se);
            updateValueUtil(ss, mid, i, diff, 2 * si + 1);
            updateValueUtil(mid + 1, se, i, diff, 2 * si + 2);
        }
    }
    static boolean checkbound(int x , int y , int m , int n){
        if(x<0 || x>=m || y<0 || y>=n)return false;
        return true;
    }
    static void printarr(int[][] a){
        int m = a.length , n = a[0].length;
        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                System.out.print(a[i][j]+" ");
            }
            System.out.println();
        }
    }
    static void printarr(char[][] a){
        int m = a.length , n = a[0].length;
        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                System.out.print(a[i][j]+" ");
            }
            System.out.println();
        }
    }
    static void printarr(int[] a){
        int n = a.length;
        StringBuilder sb = new StringBuilder();
            for(int j=0;j<n;j++){
                sb.append(a[j]+" ");//System.out.print(a[j]+" ");
            }
            System.out.println(sb);

        
    }

    static void revarr(int[] a ){
        int i=0,j=a.length-1;
        while(i<j){
            int tem = a[i];
            a[i]=a[j];
            a[j]=tem;
            i++;j--;
        }
        //return a;
    }
   
    

     static boolean[] sieveOfEratosthenes(int n)
    {
        // Create a boolean array
        // "prime[0..n]" and
        // initialize all entries
        // it as true. A value in
        // prime[i] will finally be
        // false if i is Not a
        // prime, else true.
        boolean prime[] = new boolean[n + 1];
        for (int i = 0; i <= n; i++)
            prime[i] = true;
 
        for (int p = 2; p * p <= n; p++)
        {
            // If prime[p] is not changed, then it is a
            // prime
            if (prime[p] == true)
            {
                // Update all multiples of p
                for (int i = p * p; i <= n; i += p)
                    prime[i] = false;
            }
        }
        prime[1]=false;
 
        return prime;
    }
    static int gcd(int a, int b)
    {
        if (a == 0)
            return b;
         
        return gcd(b%a, a);
    }
    static int lcm(int a, int b)
    {
        return (a / gcd(a, b)) * b;
    }
    public static class Pair{
        int x;
        int y;
 
        public Pair(int x, int y){
            this.x = x;
            this.y = y;
        }
 
         
    }
    
    static int[] st;
    static FastReader br=new FastReader();//(new InputStreamReader(System.in));
/*

*/
///////////////////////////////////////////////////////////


 
 

    public static void main (String[] args) throws java.lang.Exception
    {
        // your code goes here
        int t=1;
        br=new FastReader();
               // t=br.ni();//Integer.parseInt(br.readLine().trim());
        StringBuilder sb=new StringBuilder();
          
    in1 :   while(t-->0)
        {
            // sb.append(solve()+"\n");
        
                    solve();
        }
          
            //          System.out.println("OUTPUT:::");
    
        System.out.println(sb);
    }
    ///end main
    static void solve(){
  int n = br.ni();
  ArrayList<ArrayList<Integer>> adj = new ArrayList<>();
  for(int i=0;i<n;i++)adj.add(new ArrayList<>());
    for(int i=0;i<n;i++){
        int sou = i;
        int dest = br.ni() - 1;

         adj.get(sou).add(dest);
        adj.get(dest).add(sou);

    }
   // System.out.println(adj);

    int ans = 0;
    boolean[] vis = new boolean[n];
    for(int i=0;i<n;i++){
        if(!vis[i]){
            DFS(adj , vis , i );
           // if(adj.get(i).size()!=0)
            ans++;
        }
    }
    System.out.println(ans);

    }
     
//end solve
     static void DFS(ArrayList<ArrayList<Integer>> adj , boolean[] vis , int sou ){
        vis[sou] = true;
        ArrayList<Integer> al = adj.get(sou);
        for(int i=0;i<al.size();i++){
            /// if(al.get(i) == parent)continue;
            if(!vis[al.get(i)]){DFS(adj , vis , al.get(i)  );}
        }
     }
      
      
    }
    //end class    
    /*
     
   1 2 3 4 5
   3 4 1 2


      */