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.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.*;

import javax.lang.model.type.IntersectionType;
import javax.swing.text.html.CSS;
public class codeforces {
    static int n=20000;
    static ArrayList<Integer>[] al=new ArrayList[n];
    static boolean vis[]=new boolean[n+1];

    static int count[]=new int[n+90];
    static int c=0;

    static void DFS(int x)
    {
        vis[x]=true;
        for(int child:al[x]){
            if(!vis[child]){
                DFS(child);
            }
        }
    }
    public static void main(String[] args) {
        PrintWriter out = new PrintWriter(System.out);
        InputReader sc = new InputReader(System.in);
            int ans=0;
            int n=sc.nextInt();
            int[] p=new int[n+1];
            for(int i=1;i<n+1;i++)
                p[i]= sc.nextInt();
            for(int i=0;i<=10001;i++)
                al[i]=new ArrayList<>();
            for(int i=1;i<=n;i++)
            {
                al[i].add(p[i]);
                al[p[i]].add(i);
            }



            for(int i=1;i<=n;i++)
            {
                if(vis[i])
                    continue;
                else {
                    ans++;
                    DFS(i);

                }
            }
            System.out.println(ans);

        }



    static class InputReader {
        private InputStream in;
        private byte[] buffer = new byte[1024];
        private int curbuf;
        private int lenbuf;
        public InputReader(InputStream in) {
            this.in = in;
            this.curbuf = this.lenbuf = 0;
        }
        public boolean hasNextByte() {
            if (curbuf >= lenbuf) {
                curbuf = 0;
                try {
                    lenbuf = in.read(buffer);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (lenbuf <= 0)
                    return false;
            }
            return true;
        }

        private int readByte() {
            if (hasNextByte())
                return buffer[curbuf++];
            else
                return -1;
        }

        private boolean isSpaceChar(int c) {
            return !(c >= 33 && c <= 126);
        }

        private void skip() {
            while (hasNextByte() && isSpaceChar(buffer[curbuf]))
                curbuf++;
        }

        public boolean hasNext() {
            skip();
            return hasNextByte();
        }

        public String next() {
            if (!hasNext())
                throw new NoSuchElementException();
            StringBuilder sb = new StringBuilder();
            int b = readByte();
            while (!isSpaceChar(b)) {
                sb.appendCodePoint(b);
                b = readByte();
            }
            return sb.toString();
        }

        public int nextInt() {
            if (!hasNext())
                throw new NoSuchElementException();
            int c = readByte();
            while (isSpaceChar(c))
                c = readByte();
            boolean minus = false;
            if (c == '-') {
                minus = true;
                c = readByte();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res = res * 10 + c - '0';
                c = readByte();
            } while (!isSpaceChar(c));
            return (minus) ? -res : res;
        }

        public long nextLong() {
            if (!hasNext())
                throw new NoSuchElementException();
            int c = readByte();
            while (isSpaceChar(c))
                c = readByte();
            boolean minus = false;
            if (c == '-') {
                minus = true;
                c = readByte();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res = res * 10 + c - '0';
                c = readByte();
            } while (!isSpaceChar(c));
            return (minus) ? -res : res;
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public int[] nextIntArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++)
                a[i] = nextInt();
            return a;
        }

        public long[] nextLongArray(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++)
                a[i] = nextLong();
            return a;
        }

        public char[][] nextCharMap(int n, int m) {
            char[][] map = new char[n][m];
            for (int i = 0; i < n; i++)
                map[i] = next().toCharArray();
            return map;
        }
    }
}
class SegTree<S> {
    final int MAX;

    final int N;
    final java.util.function.BinaryOperator<S> op;
    final S E;

    final S[] data;

    @SuppressWarnings("unchecked")
    public SegTree(int n, java.util.function.BinaryOperator<S> op, S e) {
        this.MAX = n;
        int k = 1;
        while (k < n) k <<= 1;
        this.N = k;
        this.E = e;
        this.op = op;
        this.data = (S[]) new Object[N << 1];
        java.util.Arrays.fill(data, E);
    }

    public SegTree(S[] dat, java.util.function.BinaryOperator<S> op, S e) {
        this(dat.length, op, e);
        build(dat);
    }

    private void build(S[] dat) {
        int l = dat.length;
        System.arraycopy(dat, 0, data, N, l);
        for (int i = N - 1; i > 0; i--) {
            data[i] = op.apply(data[i << 1 | 0], data[i << 1 | 1]);
        }
    }

    public void set(int p, S x) {
        exclusiveRangeCheck(p);
        data[p += N] = x;
        p >>= 1;
        while (p > 0) {
            data[p] = op.apply(data[p << 1 | 0], data[p << 1 | 1]);
            p >>= 1;
        }
    }

    public S get(int p) {
        exclusiveRangeCheck(p);
        return data[p + N];
    }

    public S prod(int l, int r) {
        if (l > r) {
            throw new IllegalArgumentException(
                    String.format("Invalid range: [%d, %d)", l, r)
            );
        }
        inclusiveRangeCheck(l);
        inclusiveRangeCheck(r);
        S sumLeft = E;
        S sumRight = E;
        l += N; r += N;
        while (l < r) {
            if ((l & 1) == 1) sumLeft = op.apply(sumLeft, data[l++]);
            if ((r & 1) == 1) sumRight = op.apply(data[--r], sumRight);
            l >>= 1; r >>= 1;
        }
        return op.apply(sumLeft, sumRight);
    }

    public S allProd() {
        return data[1];
    }

    public int maxRight(int l, java.util.function.Predicate<S> f) {
        inclusiveRangeCheck(l);
        if (!f.test(E)) {
            throw new IllegalArgumentException("Identity element must satisfy the condition.");
        }
        if (l == MAX) return MAX;
        l += N;
        S sum = E;
        do {
            l >>= Integer.numberOfTrailingZeros(l);
            if (!f.test(op.apply(sum, data[l]))) {
                while (l < N) {
                    l = l << 1;
                    if (f.test(op.apply(sum, data[l]))) {
                        sum = op.apply(sum, data[l]);
                        l++;
                    }
                }
                return l - N;
            }
            sum = op.apply(sum, data[l]);
            l++;
        } while ((l & -l) != l);
        return MAX;
    }

    public int minLeft(int r, java.util.function.Predicate<S> f) {
        inclusiveRangeCheck(r);
        if (!f.test(E)) {
            throw new IllegalArgumentException("Identity element must satisfy the condition.");
        }
        if (r == 0) return 0;
        r += N;
        S sum = E;
        do {
            r--;
            while (r > 1 && (r & 1) == 1) r >>= 1;
            if (!f.test(op.apply(data[r], sum))) {
                while (r < N) {
                    r = r << 1 | 1;
                    if (f.test(op.apply(data[r], sum))) {
                        sum = op.apply(data[r], sum);
                        r--;
                    }
                }
                return r + 1 - N;
            }
            sum = op.apply(data[r], sum);
        } while ((r & -r) != r);
        return 0;
    }

    private void exclusiveRangeCheck(int p) {
        if (p < 0 || p >= MAX) {
            throw new IndexOutOfBoundsException(
                    String.format("Index %d out of bounds for the range [%d, %d).", p, 0, MAX)
            );
        }
    }

    private void inclusiveRangeCheck(int p) {
        if (p < 0 || p > MAX) {
            throw new IndexOutOfBoundsException(
                    String.format("Index %d out of bounds for the range [%d, %d].", p, 0, MAX)
            );
        }
    }
}
class MathLib{
    private static long safe_mod(long x, long m){
        x %= m;
        if(x<0) x += m;
        return x;
    }

    private static long[] inv_gcd(long a, long b){
        a = safe_mod(a, b);
        if(a==0) return new long[]{b,0};

        long s=b, t=a;
        long m0=0, m1=1;
        while(t>0){
            long u = s/t;
            s -= t*u;
            m0 -= m1*u;
            long tmp = s; s = t; t = tmp;
            tmp = m0; m0 = m1; m1 = tmp;
        }
        if(m0<0) m0 += b/s;
        return new long[]{s,m0};
    }

    public static long gcd(long a, long b){
        a = java.lang.Math.abs(a);
        b = java.lang.Math.abs(b);
        return inv_gcd(a, b)[0];
    }
    public static long lcm(long a, long b){
        a = java.lang.Math.abs(a);
        b = java.lang.Math.abs(b);
        return a / gcd(a,b) * b;
    }

    public static long pow_mod(long x, long n, int m){
        assert n >= 0;
        assert m >= 1;
        if(m == 1)return 0L;
        x = safe_mod(x, m);
        long ans = 1L;
        while(n > 0){
            if((n&1) == 1) ans = (ans * x) % m;
            x = (x*x) % m;
            n >>>= 1;
        }
        return ans;
    }

    public static long[] crt(long[] r, long[] m){
        assert(r.length == m.length);
        int n = r.length;

        long r0=0, m0=1;
        for(int i=0; i<n; i++){
            assert(1 <= m[i]);
            long r1 = safe_mod(r[i], m[i]), m1 = m[i];
            if(m0 < m1){
                long tmp = r0; r0 = r1; r1 = tmp;
                tmp = m0; m0 = m1; m1 = tmp;
            }
            if(m0%m1 == 0){
                if(r0%m1 != r1) return new long[]{0,0};
                continue;
            }

            long[] ig = inv_gcd(m0, m1);
            long g = ig[0], im = ig[1];

            long u1 = m1/g;
            if((r1-r0)%g != 0) return new long[]{0,0};

            long x = (r1-r0) / g % u1 * im % u1;

            r0 += x * m0;
            m0 *= u1;
            if(r0<0) r0 += m0;
            //System.err.printf("%d %d\n", r0, m0);
        }
        return new long[]{r0, m0};
    }
    public static long floor_sum(long n, long m, long a, long b){
        long ans = 0;
        if(a >= m){
            ans += (n-1) * n * (a/m) / 2;
            a %= m;
        }
        if(b >= m){
            ans += n * (b/m);
            b %= m;
        }

        long y_max = (a*n+b) / m;
        long x_max = y_max * m - b;
        if(y_max == 0) return ans;
        ans += (n - (x_max+a-1)/a) * y_max;
        ans += floor_sum(y_max, a, m, (a-x_max%a)%a);
        return ans;
    }

    public static java.util.ArrayList<Long> divisors(long n){
        java.util.ArrayList<Long> divisors = new ArrayList<>();
        java.util.ArrayList<Long> large = new ArrayList<>();

        for(long i=1; i*i<=n; i++) if(n%i==0){
            divisors.add(i);
            if(i*i<n) large.add(n/i);
        }
        for(int p=large.size()-1; p>=0; p--){
            divisors.add(large.get(p));
        }
        return divisors;
    }
}