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.*;
    import java.math.*;
     
    public class bhaa {
     
        InputStream is;
        PrintWriter o;
        /////////////////// CODED++ BY++ ++ ++ ++ BHAVYA++ ARORA++ ++ ++ ++ FROM++ JAYPEE++ INSTITUTE++ OF++ INFORMATION++ TECHNOLOGY++ ////////////////
     
    ///////////////////////// Make it work, make it right, make it fast. Make it work, make it right, make it fast. Make it work, make it right, make it fast. Make it work, make it right, make it fast. /////////////////
     
    
        
        void solve() {
			int n=ni();
			DJset d1=new DJset(n);
			for(int i=0;i<n;i++)
			{
				int x=ni()-1;
				d1.union(i,x);
			}   
			o.println(d1.countsets());

        
     
            
            
     
            
     
     
        }
     
     
     
     
     
     
       
     
     
        
     
     
     
     
     
     
     
     
     
     
     
     
        
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
        //---------- I/O Template ----------
        
        public static void main(String[] args) { new bhaa().run(); }
        void run() { 
            is = System.in; 
            o = new PrintWriter(System.out);
            solve();
            o.flush();
        }
        
        byte input[] = new byte[1024];
        int len = 0, ptr = 0;
        
        int readByte() { 
            if(ptr >= len) { ptr = 0; 
                try { len = is.read(input); } 
                catch(IOException e) { throw new InputMismatchException(); } 
                if(len <= 0) { return -1; } 
            } return input[ptr++];
        }
        boolean isSpaceChar(int c) { return !( c >= 33 && c <= 126 ); }
        int skip() { 
            int b = readByte(); 
            while(b != -1 && isSpaceChar(b)) { b = readByte(); } 
            return b;
        }
        
        char nc() { return (char)skip(); }
        String ns() { 
            int b = skip(); 
            StringBuilder sb = new StringBuilder(); 
            while(!isSpaceChar(b)) { sb.appendCodePoint(b); b = readByte(); } 
            return sb.toString();
        }
        String nLine() { 
            int b = skip(); 
            StringBuilder sb = new StringBuilder(); 
            while( !(isSpaceChar(b) && b != ' ') ) { sb.appendCodePoint(b); b = readByte(); } 
            return sb.toString();
        }
        int ni() { 
            int n = 0, b = readByte(); 
            boolean minus = false; 
            while(b != -1 && !( (b >= '0' && b <= '9') || b == '-')) { b = readByte(); } 
            if(b == '-') { minus = true; b = readByte(); } 
            if(b == -1) { return -1; }  //no input 
            while(b >= '0' && b <= '9') { n = n * 10 + (b - '0'); b = readByte(); } 
            return minus ? -n : n;
        }
        long nl() { 
            long n = 0L;    int b = readByte(); 
            boolean minus = false; 
            while(b != -1 && !( (b >= '0' && b <= '9') || b == '-')) { b = readByte(); } 
            if(b == '-') { minus = true; b = readByte(); } 
            while(b >= '0' && b <= '9') { n = n * 10 + (b - '0'); b = readByte(); } 
            return minus ? -n : n;
        }
     
        double nd() { return Double.parseDouble(ns()); }
        float nf() { return Float.parseFloat(ns()); }
        int[] nia(int n) { 
            int a[] = new int[n]; 
            for(int i = 0; i < n; i++) { a[i] = ni(); } 
            return a;
        }
        long[] nla(int n) { 
            long a[] = new long[n]; 
            for(int i = 0; i < n; i++) { a[i] = nl(); } 
            return a;
        }
        int [][] nim(int n)
        {
            int mat[][]=new int[n][n];
            for(int i=0;i<n;i++)
            {
                for(int j=0;j<n;j++)
                {
                    mat[i][j]=ni();
                }
            }
            return mat;
        }
        long [][] nlm(int n)
        {
            long mat[][]=new long[n][n];
            for(int i=0;i<n;i++)
            {
                for(int j=0;j<n;j++)
                {
                    mat[i][j]=nl();
                }
            }
            return mat;
        }
        
     
     
     
     
        
        char[] ns(int n) { 
            char c[] = new char[n]; 
            int i, b = skip(); 
            for(i = 0; i < n; i++) { 
                if(isSpaceChar(b)) { break; } 
                c[i] = (char)b; b = readByte(); 
            } return i == n ? c : Arrays.copyOf(c,i);
        }
        void piarr(int arr[])
        {
            for(int i=0;i<arr.length;i++)
            {
                o.print(arr[i]+" ");
     
            }
            o.println();
        }
        void plarr(long arr[])
        {
            for(int i=0;i<arr.length;i++)
            {
                o.print(arr[i]+" ");
     
            }
            o.println();
        }
        
        void pimat(int mat[][])
        {
            for(int i=0;i<mat.length;i++)
            {
                for(int j=0;j<mat[0].length;j++)
                {
                    o.print(mat[i][j]+" ");
                }
                o.println();
            }
        }
        void plmat(long mat[][])
        {
            for(int i=0;i<mat.length;i++)
            {
                for(int j=0;j<mat[0].length;j++)
                {
                    o.print(mat[i][j]+" ");
                }
                o.println();
            }
     
        }
       static class DJset
{
    int n;
    ty1 arr[];
    class ty1
    {
        int rank;
        int par;
        ty1(int p,int r)
        {
            par=p;
            rank=r;
        }
    }
    DJset(int nu)
    {
        n=nu;
        arr=new ty1[n];
        for(int i=0;i<n;i++)
        {
            arr[i]=new ty1(i,1);
        }

    }
    int find(int x)
    {
        if(arr[x].par!=x)
        {
            arr[x].par=find(arr[x].par);
        }
        return arr[x].par;
    }
    void union(int x,int y)
    {
        x=find(x);
        y=find(y);
        if(x!=y)
        {
            if(arr[x].rank<arr[y].rank)
            {
                arr[x].par=y;
            }
            else if(arr[y].rank<arr[x].rank)
            {
                arr[y].par=x;
            }
            else
            {
                arr[x].rank++;
                arr[y].par=x;

            }
        }
    }
    public String toString()
    {
        String res="";
        for(int i=0;i<n;i++)
        {
            res+=(arr[i].par+" ");
        }
        
        return res;
    }
    public int countsets()
    {
        int res=0;
        for(int i=0;i<n;i++)
        {
            if(arr[i].par==i)
            {
                res++;
            }
        }
        return res;
    }

    

    }
    
     
     
     
     
        //////////////////////////////////// template finished //////////////////////////////////////
     
     
     
    }