import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;

/*
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/**
 *
 * @author cteam014
 */
public class Monsters {
    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    
    
    public void solve() throws  Exception {
        String line;
        while ((line = reader.readLine()) != null) {
            int N = Integer.parseInt(line);
            int count = 0;
            int[] rooms = new int[N+1];
            line = reader.readLine();
            String[] a = line.split(" ");
            for (int i = 0; i < a.length; i++) {
                rooms[i+1] = Integer.parseInt(a[i]);
            }
            boolean change = true;
            while(change){
                change = false;
                for (int i = 1; i < rooms.length; i++) {
                if(rooms[i] != i){
                    int temp = rooms[i];
                    int temp2 = rooms[temp];
                    rooms[temp] = temp;
                    rooms[i] = temp2;
                    count++;
                    change = true;
                }
            }
            }
            
            System.out.println(count);
        }   
    }
    
    public static void main(String[] args) throws Exception {
        new Monsters().solve();
    }
}