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:
import java.io.*;
import java.util.*;

public class ProblemC2 {

    public static void main(String[] args) throws IOException {
        init();
        new ProblemC2().run();
        out.flush();
        out.close();
    }

    static void init() throws IOException {
        in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
        out = new PrintWriter(new OutputStreamWriter(System.out));
        in.ordinaryChars(0, 65535);
        in.wordChars(0, 65535);
        in.whitespaceChars(' ', ' ');
        in.whitespaceChars('\n', '\n');
        in.whitespaceChars('\r', '\r');
    }

    // класс для пар
    class Pair<L, R> {
        private final L X;
        private final R Y;

        public Pair(L X, R Y) {
            this.X = X;
            this.Y = Y;
        }

        public L getX() {
            return X;
        }

        public R getY() {
            return Y;
        }

        @Override
        public int hashCode() {
            return X.hashCode() ^ Y.hashCode();
        }

        @Override
        public boolean equals(Object o) {
            if (!(o instanceof Pair)) return false;
            Pair pairo = (Pair) o;
            return X.equals(pairo.getX()) && Y.equals(pairo.getY());
        }
    }

    static final long INFL = 200000000000000000L;
    static final int INF = 2000000000;
    static final boolean DEBUG = true;

    static StreamTokenizer in;
    static PrintWriter out;

    static void print(String s) {
        print(s, 0);
    }

    static void print(String s, int debug) {
        if (debug == 0 || DEBUG) {
            out.print(s);
        }
    }

    static void println(String s) {
        println(s, 0);
    }

    static void println(String s, int debug) {
        if (debug == 0 || DEBUG) {
            out.println(s);
        }
    }

    static void printArray(int[] arr) {
        println(Arrays.toString(arr));
    }

    static void printArray(char[] arr) {
        println(Arrays.toString(arr));
    }

    static void printArray(String[] arr) {
        println(Arrays.toString(arr));
    }

    static void sort(int[] a) {
        Random rnd = new Random();
        for (int i = a.length - 1; i > 0; i--) {
            int index = rnd.nextInt(i);
            a[i] ^= a[index];
            a[index] ^= a[i];
            a[i] ^= a[index];
        }
        Arrays.sort(a);
    }

    static char[] inChars;
    static int inCharsInd;

    static String next() throws IOException {
        in.nextToken();
        return in.sval;
    }

    static char nextChar() throws IOException {
        while (inChars == null || inCharsInd >= inChars.length) {
            inChars = next().toCharArray();
            inCharsInd = 0;
        }
        return inChars[inCharsInd++];
    }

    static int nextInt() throws IOException {
        return Integer.valueOf(next());
    }

    static double nextDouble() throws IOException {
        return Double.valueOf(next());
    }

    static long nextLong() throws IOException {
        return Long.valueOf(next());
    }

    private void run() throws IOException {
        solve();
    }

    int K, L, M, N, P;

    private void solve() throws IOException {

        N = nextInt();
        Set<Integer> set = new HashSet<>();
        int answer = 0;
        for (int i = 0; i < N; i++) {
            int next = nextInt() - 1;
            if (next == i) {
                answer++;
            } else {
                set.add(next);
            }
        }
        answer += set.size()/2;
        System.out.println(answer);
    }

}