import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;


/**5
 *
 * @author muran4
 */
public class Monsters {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException {
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
        
        String line;
        String[] arr;
        int[] serie;
   
        int num;
        while((line = input.readLine())!=null){
            num = Integer.parseInt(line);
            line = input.readLine();
            //arr = line.split(" ");
            
//            Scanner in = new Scanner(line);
int position[] = new int[num+1];
            
            serie = new int[num];
//            position = new int[num+1];
            int pocet = 0;
            int x = 0;
            arr = line.split(" ");
            for (int i = 0; i < num; i++) {
                serie[i] = Integer.parseInt(arr[i]);
                position[serie[i]] = i;
//                if(serie[i]<i+1)
//                System.out.println(serie[serie[i]-1] +" "+ (i+1)+"");
//                if(serie[i]<i+1 && serie[serie[i]-1] == i+1)pocet--;


//                if(serie[i]!=i)pocet++;
//                System.out.println(i+" "+serie[serie[i]]+" "+serie[i]);
//                if(i> serie[i] && serie[serie[i]] == i)System.out.println(i);
//                if(i> serie[i] && serie[serie[i]] == i)pocet--;
//                if(i == serie[i])x++;
            }
            
            int pos;
            int temp;
            
            for (int i = 0; i < num; i++) {
                if(serie[i]!=i+1){
                    temp = serie[i];
                    serie[i] = i+1;
                    position[temp] = position[serie[i]];
                    serie[position[serie[i]]] = temp;
                    pocet++;
                }
            }
            System.out.println(pocet);
//            int out = num+pocet-1;
//            if(x > 0)out-=(x-1);
////            System.out.println(num+pocet-1+" "+(x-1));
//            System.out.println(out);
            
        }
    }
    
}