/*
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 */

import java.io.*;
import java.io.BufferedReader;
import java.io.InputStreamReader;

/**
 *
 * @author cteam056
 */

// předělat na Main
class Main {

    public static BufferedReader in; 
    private static String line;
    private static int[] monsters;
    private static String [] strMonsters;
    private static int N;
    /**
     * @param args the command line arguments
     * @throws java.io.IOException
     */
    public static void main(String[] args) throws IOException {
        // TODO code application logic here
        in = new BufferedReader(new InputStreamReader(System.in));
        
        
        
        
        
        while((line = in.readLine()) != null && !line.isEmpty()) 
        {
            N = Integer.parseInt(line);
            monsters = new int[N];
            
            line = in.readLine();
            strMonsters = line.split(" ");
            
            for(int i = 0; i < N; i++)
            {
                monsters[i] = Integer.parseInt(strMonsters[i]);
            }
            
            System.out.println(seradMonstra());
        }
    }
    
    private static int seradMonstra()
    {
        int retVal = 0;
        int tmp;
        
        for(int i = 0; i < N; i++)
        {
            if (monsters[i] != i + 1)
            {
                tmp = monsters[i];
                monsters[i] = monsters[tmp - 1];
                monsters[tmp - 1] = tmp;
                retVal++;
                i--;
            }
        }
        
        return retVal;
    }
}